A lot of timeouts at least in dovecot since last update

[tehXor]

Since the last update to the current master branch dovecot is extremely inconsistent. Logins regularly take very long and sometimes eventually even fail completely due to timeouts. I'm not sure if other containers have problems, too. Overall fetching mails feels very sluggish, especially when using SOGo (which often also fails completely) but also in native clients.
We did some recreates and restarts (even of the host machine) without luck so far.

Here are some dovecot log entries which seem strange to me. I couldn't find log entries in other containers that seemed problematic so far (but this doesn't mean there are none).

dovecot-mailcow_1    | ==> /var/log/mail.log <==
dovecot-mailcow_1    | 2017-03-16 15:09:35 imap-login: Error: master(imap): Auth request timed out (received 0/12 bytes)
dovecot-mailcow_1    | 2017-03-16 15:09:35 imap-login: Info: Internal login failure (pid=420 id=1) (internal failure, 1 successful auths): user=<user1@->, method=PLAIN, rip=0.0.0.0, lip=172.22.1.7, TLS, TLSv1.2 with cipher DHE-RSA-AES256-GCM-SH         A384 (256/256 bits)
dovecot-mailcow_1    | 2017-03-16 15:09:37 imap-login: Error: master(imap): Auth request timed out (received 0/12 bytes)
dovecot-mailcow_1    | 2017-03-16 15:09:37 imap-login: Info: Internal login failure (pid=422 id=1) (internal failure, 1 successful auths): user=<user2@->, method=PLAIN, rip=0.0.0.0, lip=172.22.1.7, TLS, TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA         384 (256/256 bits)
dovecot-mailcow_1    | 2017-03-16 15:09:45 imap: Error: Login client disconnected too early
dovecot-mailcow_1    | 2017-03-16 15:09:45 imap: Error: Internal auth failure (client-pid=420 client-id=1)
dovecot-mailcow_1    | 2017-03-16 15:09:45 auth: Error: Master requested auth for nonexistent client 420
dovecot-mailcow_1    | 2017-03-16 15:09:45 pop3-login: Info: Login: user=<user3@->, method=PLAIN, rip=0.0.0.0, lip=172.22.1.7, mpid=431, TLS, TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)
dovecot-mailcow_1    | 2017-03-16 15:09:45 pop3-login: Info: Login: user=<user4@->, method=PLAIN, rip=0.0.0.0, lip=172.22.1.7, mpid=432, TLS, TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
dovecot-mailcow_1    | 2017-03-16 15:09:45 imap: Error: Login client disconnected too early
dovecot-mailcow_1    | 2017-03-16 15:09:45 auth: Error: Master requested auth for nonexistent client 422
dovecot-mailcow_1    | 2017-03-16 15:09:45 imap: Error: Internal auth failure (client-pid=422 client-id=1)
dovecot-mailcow_1    | 2017-03-16 15:09:45 imap-login: Info: Login: user=<user5@->, method=PLAIN, rip=0.0.0.0, lip=172.22.1.7, mpid=434, TLS, TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)
dovecot-mailcow_1    | 2017-03-16 15:09:45 imap-login: Info: Login: user=<user6@->, method=PLAIN, rip=0.0.0.0, lip=172.22.1.7, mpid=435, TLS, TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)
dovecot-mailcow_1    | 2017-03-16 15:09:45 imap(user6@-): Info: Connection closed in=48 out=757
dovecot-mailcow_1    | 2017-03-16 15:09:46 pop3(user4@-): Info: Disconnected: Logged out top=0/0, retr=8/240361, del=8/9, size=448269
dovecot-mailcow_1    | 2017-03-16 15:09:47 pop3(user3@-): Info: Disconnected: Logged out top=0/0, retr=3/1056147, del=0/3, size=1056087

or

dovecot-mailcow_1    | ==> /var/log/mail.log <==
dovecot-mailcow_1    | 2017-03-16 15:11:08 imap-login: Info: Login: user=<user2@->, method=PLAIN, rip=0.0.0.0, lip=172.22.1.7, mpid=453, TLS, TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)
dovecot-mailcow_1    | 2017-03-16 15:11:08 imap(user2@-): Info: Logged out in=66 out=1202
dovecot-mailcow_1    | 2017-03-16 15:11:24 imap(user5@-): Info: Connection closed in=1035 out=6595
dovecot-mailcow_1    | 2017-03-16 14:51:53 log: Warning: Time moved backwards by 1173 seconds.
dovecot-mailcow_1    | 2017-03-16 14:51:53 imap-login: Warning: Time moved backwards by 1174 seconds.
dovecot-mailcow_1    | 2017-03-16 14:51:53 imap: Fatal: Time just moved backwards by 1174 seconds. This might cause a lot of problems, so I'll just kill myself now. http://wiki2.dovecot.org/TimeMovedBackwards
dovecot-mailcow_1    | 2017-03-16 14:51:53 master: Warning: Time moved backwards by 1173 seconds, waiting for 180 secs until new services are launched again.
dovecot-mailcow_1    | 2017-03-16 14:51:53 anvil: Warning: Time moved backwards by 1171 seconds.
dovecot-mailcow_1    | 2017-03-16 14:51:53 config: Warning: Time moved backwards by 1171 seconds.
dovecot-mailcow_1    | 2017-03-16 14:51:53 imap: Fatal: Time just moved backwards by 1144 seconds. This might cause a lot of problems, so I'll just kill myself now. http://wiki2.dovecot.org/TimeMovedBackwards
dovecot-mailcow_1    | 2017-03-16 14:51:53 imap-login: Warning: Time moved backwards by 1054 seconds.

This is just a small part but it looks like it covers the most obvious error messages which are currently in the log. Any ideas?

[tehXor]

So we had one misconfigured time source in our network which caused the docker host of dovecot-mailcow to switch to a wrong time for just a few seconds until it switched back to the right time again. Eliminating this problem got rid of the time moved errors and so far it seems this also eliminated the login problems.
It's a bit strange though as this misconfigured time source was active for over one month and dovecot-mailcow had no problems with it before. Still I'm assuming this fixed the problem for now.