This bug was in T4241, client couldn't connect to openconnect server and logs from the server site like:
Feb 16 19:46:03 r4 ocserv[2409]: main:192.168.122.1:44480 user disconnected (reason: unspecified, rx: 0, tx: 0) Feb 16 19:46:03 r4 ocserv[2409]: main:192.168.122.1:44482 user disconnected (reason: unspecified, rx: 0, tx: 0) ^C
It was tested with self-signed certificates.