The Caddy file I posted was the whole file. I stripped it down even further for testing (to the bare min). Here is a log where I contact the server and get the login prompt:
2022/03/11 00:09:39 info tls.cache.maintenance started background certificate maintenance {"cache": "0xc000374070"}
2022/03/11 00:09:39 debug http starting server loop {"address": "[::]:8843", "http3": false, "tls": true}
2022/03/11 00:09:39 debug http starting server loop {"address": "[::]:80", "http3": false, "tls": false}
2022/03/11 00:09:39 info http enabling automatic TLS certificate management {"domains": ["service.awesomedomain.com"]}
2022/03/11 00:09:39 debug tls loading managed certificate {"domain": "service.awesomedomain.com", "expiration": "2022/05/12 19:14:03", "issuer_key": "acme-v02.api.letsencrypt.org-directory", "storage": "FileStorage:C:\\Users\\adminperson\\AppData\\Roaming\\Caddy"}
2022/03/11 00:09:39 debug tls.cache added certificate to cache {"subjects": ["service.awesomedomain.com"], "expiration": "2022/05/12 19:14:03", "managed": true, "issuer_key": "acme-v02.api.letsencrypt.org-directory", "hash": "0ded9b5bf5c79d0fe7633fe3c4e9e9301d2e0c095e3cfa65f00004bd13d403c0", "cache_size": 1, "cache_capacity": 10000}
2022/03/11 00:09:39 info tls cleaning storage unit {"description": "FileStorage:C:\\Users\\adminperson\\AppData\\Roaming\\Caddy"}
2022/03/11 00:09:39 info tls finished cleaning storage units
2022/03/12 00:01:29 info tls.cache.maintenance started background certificate maintenance {"cache": "0xc000386150"}
2022/03/12 00:01:29 info http enabling automatic HTTP->HTTPS redirects {"server_name": "srv0"}
2022/03/12 00:01:29 info tls cleaning storage unit {"description": "FileStorage:C:\\Users\\adminperson\\AppData\\Roaming\\Caddy"}
2022/03/12 00:01:29 debug http starting server loop {"address": "[::]:8443", "http3": false, "tls": true}
2022/03/12 00:01:29 debug http starting server loop {"address": "[::]:80", "http3": false, "tls": false}
2022/03/12 00:01:29 info http enabling automatic TLS certificate management {"domains": ["service.awesomedomain.com"]}
2022/03/12 00:01:29 info tls finished cleaning storage units
2022/03/12 00:01:29 debug tls loading managed certificate {"domain": "service.awesomedomain.com", "expiration": "2022/05/12 19:14:03", "issuer_key": "acme-v02.api.letsencrypt.org-directory", "storage": "FileStorage:C:\\Users\\adminperson\\AppData\\Roaming\\Caddy"}
2022/03/12 00:01:29 debug tls.cache added certificate to cache {"subjects": ["service.awesomedomain.com"], "expiration": "2022/05/12 19:14:03", "managed": true, "issuer_key": "acme-v02.api.letsencrypt.org-directory", "hash": "0ded9b5bf5c79d0fe7633fe3c4e9e9301d2e0c095e3cfa65f00004bd13d403c0", "cache_size": 1, "cache_capacity": 10000}
2022/03/12 00:23:13 debug tls.handshake choosing certificate {"identifier": "service.awesomedomain.com", "num_choices": 1}
2022/03/12 00:23:13 debug tls.handshake default certificate selection results {"identifier": "service.awesomedomain.com", "subjects": ["service.awesomedomain.com"], "managed": true, "issuer_key": "acme-v02.api.letsencrypt.org-directory", "hash": "0ded9b5bf5c79d0fe7633fe3c4e9e9301d2e0c095e3cfa65f00004bd13d403c0"}
2022/03/12 00:23:13 debug tls.handshake matched certificate in cache {"subjects": ["service.awesomedomain.com"], "managed": true, "expiration": "2022/05/12 19:14:03", "hash": "0ded9b5bf5c79d0fe7633fe3c4e9e9301d2e0c095e3cfa65f00004bd13d403c0"}
2022/03/12 00:23:14 debug http.handlers.reverse_proxy upstream roundtrip {"upstream": "localhost:81", "duration": 0.3620526, "request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/", "headers": {"Sec-Fetch-Dest": ["document"], "X-Forwarded-For": ["111.222.229.224"], "Sec-Ch-Ua-Platform": ["\"Android\""], "User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"], "Accept": ["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9"], "Sec-Fetch-Mode": ["navigate"], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "Sec-Fetch-User": ["?1"], "Accept-Language": ["en-US,en;q=0.9"], "X-Forwarded-Proto": ["https"], "Sec-Ch-Ua-Mobile": ["?1"], "Upgrade-Insecure-Requests": ["1"], "Sec-Fetch-Site": ["none"], "Accept-Encoding": ["gzip, deflate, br"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "headers": {"Set-Cookie": ["HFS_SID_=0.514401261694729; path=/; HttpOnly"], "Content-Encoding": ["gzip"], "Content-Length": ["1092"], "Content-Type": ["text/html"], "Www-Authenticate": ["Basic realm=\"Justin's web\""], "Accept-Ranges": ["bytes"]}, "status": 401}
2022/03/12 00:23:14 error http.log.access handled request {"request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/", "headers": {"Accept": ["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9"], "Sec-Fetch-Site": ["none"], "Sec-Fetch-Mode": ["navigate"], "Accept-Encoding": ["gzip, deflate, br"], "Sec-Ch-Ua-Mobile": ["?1"], "Sec-Ch-Ua-Platform": ["\"Android\""], "Upgrade-Insecure-Requests": ["1"], "User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "Sec-Fetch-User": ["?1"], "Sec-Fetch-Dest": ["document"], "Accept-Language": ["en-US,en;q=0.9"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "common_log": "111.222.229.224 - - [11/Mar/2022:18:23:14 -0600] \"GET / HTTP/2.0\" 401 1092", "user_id": "", "duration": 0.3698629, "size": 1092, "status": 401, "resp_headers": {"Server": ["Caddy"], "Www-Authenticate": ["Basic realm=\"Justin's web\""], "Accept-Ranges": ["bytes"], "Set-Cookie": ["HFS_SID_=0.514401261694729; path=/; HttpOnly"], "Content-Encoding": ["gzip"], "Content-Length": ["1092"], "Content-Type": ["text/html"]}}
2022/03/12 00:23:38 debug http.handlers.reverse_proxy upstream roundtrip {"upstream": "localhost:81", "duration": 0.3471744, "request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/", "headers": {"Sec-Fetch-Dest": ["document"], "Accept-Encoding": ["gzip, deflate, br"], "X-Forwarded-For": ["111.222.229.224"], "X-Forwarded-Proto": ["https"], "Sec-Ch-Ua-Mobile": ["?1"], "User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"], "Sec-Ch-Ua-Platform": ["\"Android\""], "Upgrade-Insecure-Requests": ["1"], "Sec-Fetch-Mode": ["navigate"], "Accept-Language": ["en-US,en;q=0.9"], "Cache-Control": ["max-age=0"], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "Accept": ["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9"], "Sec-Fetch-Site": ["none"], "Sec-Fetch-User": ["?1"], "Cookie": ["HFS_SID_=0.514401261694729"], "Authorization": ["Basic dWw6dGlnZXIhdXBsb3VkMDAuLg=="]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "headers": {"Content-Length": ["1090"], "Content-Type": ["text/html"], "Www-Authenticate": ["Basic realm=\"Invalid login\""], "Accept-Ranges": ["bytes"], "Content-Encoding": ["gzip"]}, "status": 401}
2022/03/12 00:23:38 error http.log.access handled request {"request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/", "headers": {"Sec-Ch-Ua-Mobile": ["?1"], "Sec-Fetch-Dest": ["document"], "Accept-Encoding": ["gzip, deflate, br"], "Sec-Ch-Ua-Platform": ["\"Android\""], "User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"], "Cache-Control": ["max-age=0"], "Upgrade-Insecure-Requests": ["1"], "Sec-Fetch-Mode": ["navigate"], "Accept-Language": ["en-US,en;q=0.9"], "Sec-Fetch-User": ["?1"], "Cookie": ["HFS_SID_=0.514401261694729"], "Authorization": ["Basic dWw6dGlnZXIhdXBsb3VkMDAuLg=="], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "Accept": ["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9"], "Sec-Fetch-Site": ["none"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "common_log": "111.222.229.224 - - [11/Mar/2022:18:23:38 -0600] \"GET / HTTP/2.0\" 401 1090", "user_id": "", "duration": 0.3506184, "size": 1090, "status": 401, "resp_headers": {"Server": ["Caddy"], "Content-Encoding": ["gzip"], "Content-Length": ["1090"], "Content-Type": ["text/html"], "Www-Authenticate": ["Basic realm=\"Invalid login\""], "Accept-Ranges": ["bytes"]}}
2022/03/12 00:23:41 debug http.handlers.reverse_proxy upstream roundtrip {"upstream": "localhost:81", "duration": 0.3309601, "request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/", "headers": {"Authorization": ["Basic dWw6dGlnZXIhdXBsb3VkMDAuLg=="], "Accept-Encoding": ["gzip, deflate, br"], "Sec-Fetch-Site": ["none"], "Sec-Fetch-User": ["?1"], "Sec-Fetch-Dest": ["document"], "X-Forwarded-Proto": ["https"], "Cache-Control": ["max-age=0"], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "Accept": ["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9"], "Accept-Language": ["en-US,en;q=0.9"], "Sec-Fetch-Mode": ["navigate"], "Cookie": ["HFS_SID_=0.514401261694729"], "X-Forwarded-For": ["111.222.229.224"], "Sec-Ch-Ua-Mobile": ["?1"], "Sec-Ch-Ua-Platform": ["\"Android\""], "Upgrade-Insecure-Requests": ["1"], "User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "headers": {"Content-Length": ["1092"], "Content-Type": ["text/html"], "Www-Authenticate": ["Basic realm=\"Invalid login\""], "Accept-Ranges": ["bytes"], "Content-Encoding": ["gzip"]}, "status": 401}
2022/03/12 00:23:41 error http.log.access handled request {"request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/", "headers": {"User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"], "Sec-Fetch-Mode": ["navigate"], "Cookie": ["HFS_SID_=0.514401261694729"], "Sec-Ch-Ua-Mobile": ["?1"], "Sec-Ch-Ua-Platform": ["\"Android\""], "Upgrade-Insecure-Requests": ["1"], "Authorization": ["Basic dWw6dGlnZXIhdXBsb3VkMDAuLg=="], "Accept-Encoding": ["gzip, deflate, br"], "Sec-Fetch-Site": ["none"], "Sec-Fetch-User": ["?1"], "Sec-Fetch-Dest": ["document"], "Accept-Language": ["en-US,en;q=0.9"], "Cache-Control": ["max-age=0"], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "Accept": ["text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9"]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "common_log": "111.222.229.224 - - [11/Mar/2022:18:23:41 -0600] \"GET / HTTP/2.0\" 401 1092", "user_id": "", "duration": 0.3402134, "size": 1092, "status": 401, "resp_headers": {"Server": ["Caddy"], "Content-Type": ["text/html"], "Www-Authenticate": ["Basic realm=\"Invalid login\""], "Accept-Ranges": ["bytes"], "Content-Encoding": ["gzip"], "Content-Length": ["1092"]}}
2022/03/12 00:23:42 debug http.handlers.reverse_proxy upstream roundtrip {"upstream": "localhost:81", "duration": 0.3467776, "request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/favicon.ico", "headers": {"Accept": ["image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8"], "Sec-Fetch-Mode": ["no-cors"], "User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"], "Sec-Ch-Ua-Mobile": ["?1"], "Sec-Ch-Ua-Platform": ["\"Android\""], "Sec-Fetch-Site": ["same-origin"], "Sec-Fetch-Dest": ["image"], "Referer": ["https://service.awesomedomain.com/"], "Cookie": ["HFS_SID_=0.514401261694729"], "X-Forwarded-For": ["111.222.229.224"], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "X-Forwarded-Proto": ["https"], "Accept-Encoding": ["gzip, deflate, br"], "Accept-Language": ["en-US,en;q=0.9"], "Authorization": ["Basic dWw6dGlnZXIhdXBsb3VkMDAuLg=="]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "headers": {"Content-Type": ["text/html"], "Www-Authenticate": ["Basic realm=\"Invalid login\""], "Accept-Ranges": ["bytes"], "Content-Encoding": ["gzip"], "Content-Length": ["1092"]}, "status": 401}
2022/03/12 00:23:42 error http.log.access handled request {"request": {"remote_addr": "111.222.229.224:11605", "proto": "HTTP/2.0", "method": "GET", "host": "service.awesomedomain.com", "uri": "/favicon.ico", "headers": {"Sec-Ch-Ua-Mobile": ["?1"], "User-Agent": ["Mozilla/5.0 (Linux; Android 12; SM-S908U) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.58 Mobile Safari/537.36"], "Sec-Ch-Ua-Platform": ["\"Android\""], "Accept": ["image/avif,image/webp,image/apng,image/svg+xml,image/*,*/*;q=0.8"], "Sec-Fetch-Site": ["same-origin"], "Sec-Fetch-Mode": ["no-cors"], "Sec-Fetch-Dest": ["image"], "Sec-Ch-Ua": ["\" Not A;Brand\";v=\"99\", \"Chromium\";v=\"99\", \"Google Chrome\";v=\"99\""], "Cookie": ["HFS_SID_=0.514401261694729"], "Referer": ["https://service.awesomedomain.com/"], "Accept-Encoding": ["gzip, deflate, br"], "Accept-Language": ["en-US,en;q=0.9"], "Authorization": ["Basic dWw6dGlnZXIhdXBsb3VkMDAuLg=="]}, "tls": {"resumed": false, "version": 772, "cipher_suite": 4865, "proto": "h2", "proto_mutual": true, "server_name": "service.awesomedomain.com"}}, "common_log": "111.222.229.224 - - [11/Mar/2022:18:23:42 -0600] \"GET /favicon.ico HTTP/2.0\" 401 1092", "user_id": "", "duration": 0.3498092, "size": 1092, "status": 401, "resp_headers": {"Server": ["Caddy"], "Content-Type": ["text/html"], "Www-Authenticate": ["Basic realm=\"Invalid login\""], "Accept-Ranges": ["bytes"], "Content-Encoding": ["gzip"], "Content-Length": ["1092"]}} ```