mail.mserv.top has an A (IPv4) record (155.138.161.117) but a request to this address over port 80 did not succeed. Your web server must have at least one working IPv4 or IPv6 address.
A timeout was experienced while communicating with mail.mserv.top/155.138.161.117: Get http://mail.mserv.top/.well-known/acme-challenge/letsdebug-test: dial tcp 155.138.161.117:80: i/o timeout
Trace:
@0ms: Making a request to http://mail.mserv.top/.well-known/acme-challenge/letsdebug-test (using initial IP 155.138.161.117)
@0ms: Dialing 155.138.161.117
@10000ms: Experienced error: dial tcp 155.138.161.117:80: i/o timeout