I have an issue with an AC3 v17.3 to v17.5 (latest).
It happens randomly. The Teams works but its impossible to start a call or receive calls. I use a bit sophisticated firewall rules, but I've tried to disable the whole firewall (put allow rules on all chain, raw scope too). I've tried to drop the exisiting connection to force renew the sessions/connections but it doesn't help. The only workaround is to reboot the router.
No error log, no high CPU or memory. Other type of traffic work like charm.
I'm not a beginner in MikroTik, but I have never seen this type of issue, when nothing seems in logs or firewall stats, connections etc.
Any idead?

Think everyone is looking forward to your config
Can you please share:
Remove serial and any other private information

I'll upload the config soon.
Meanwhile I captured the traffic with wireshark and I see TCP connection issues.

Config attached.

Does anyone have any ideas?

viewtopic.php?t=85039

Is it possible outbound TCP conn from teams is timing out from the router perspective? Seems Mikrotik TCP timeout values may be more aggressive than other system defaults.

If aggressive TCP timeouts cause the issue why it isn't constant? And I tried to reset all connections from Tracking/Connections tab and it doesn't solve. At least for a short time it should resolve if it's a timeout issue, I guess.