Remote debian buster server, so can't go to console.

Yesterday it worked properly, today it has stopped responding. I can reboot it remotely, so after reboot I can reconnect, but I can only run short command like top and I lose the connection. On top, I found that 100% is clamd, but when I tried to `/etc/init.d/clamd-daemon sto` I lost the connection before typing last the letter. So I copied it next time, but it doesn't help. I wonder which logs should I try to get (via scp) for better diagnosis....