1. The problem I’m having:
I have a Caddy proxy server set up to handle IPv6 requests. When a client connects to the server on port 443, the server responds with a SYN-ACK packet, but it doesn’t receive the next step of the connection establishment (the ACK packet) from the client. This issue is consistently reproducible. I’ve verified that the client can access the corresponding service on port 5244 without any network transmission problems. The Caddy logs don’t show any output when this issue occurs, leading me to suspect that the packets aren’t even reaching the Caddy service.
2. Error messages and/or full log output:
184 1.159631 2408:8459:2e40:81:aa96:c2eb:d586:9a6e 2408:8256:2e81:85dc:ed39:f5b8:7c48:d8c9 TCP 94 37586 → 443 [SYN] Seq=0 Win=65535 Len=0 MSS=1300 SACK_PERM TSval=2028725522 TSecr=0 WS=512
185 1.159745 2408:8256:2e81:85dc:ed39:f5b8:7c48:d8c9 2408:8459:2e40:81:aa96:c2eb:d586:9a6e TCP 94 443 → 37586 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1420 WS=256 SACK_PERM TSval=95824579 TSecr=2028725522
223 2.173910 2408:8256:2e81:85dc:ed39:f5b8:7c48:d8c9 2408:8459:2e40:81:aa96:c2eb:d586:9a6e TCP 94 [TCP Retransmission] 443 → 37586 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1420 WS=256 SACK_PERM TSval=95825593 TSecr=2028725522
323 2.388674 2408:8459:2e40:81:aa96:c2eb:d586:9a6e 2408:8256:2e81:85dc:ed39:f5b8:7c48:d8c9 TCP 94 [TCP Retransmission] 37586 → 443 [SYN] Seq=0 Win=65535 Len=0 MSS=1300 SACK_PERM TSval=2028726532 TSecr=0 WS=512
3. Caddy version:
v2.7.6 h1:w0NymbG2m9PcvKWsrXO6EEkY9Ru4FJK8uQbYcev1p3A=
4. How I installed and ran Caddy:
a. System environment:
windows11, x64.
b. Command:
.\caddy.exe run
c. Service/unit/compose file:
none
d. My complete Caddy config:
p6.olimi.icu {
reverse_proxy [::1]:5244
}