I think the error is pretty clear (and it’s one we see a lot):
Timeout during connect (likely firewall problem)
100% of the time, this is a firewall problem (or some sort of network misconfiguration). 
It means that Let’s Encrypt wasn’t able to connect to your server. If you are in China, that is a likely reason. You could try using ZeroSSL just to see: Using ZeroSSL's ACME endpoint
Edit: Duh, now I see that Caddy fell back and tried ZeroSSL too, which also failed.
Yeah, definitely a problem with the network – could be China, or could be something closer to your server.