VOIP Problem in Mikrotik

Hello everyone, I would like to know if you have any solution for VoIP in Mikrotik. I only have extensions that are receiving internet from Mikrotik, the extensions are connected to a remote server, the problems are the following, randomly sometimes the extensions lose registration, if I access Mikrotik and go to IP firewall connections and clear the extension connections, they re-authenticate immediately, this is one of the problems, another happens when failover occurs, when the first link goes down and the second one comes on, the extensions continue to work but when the first one comes back, the extensions lose registration and also only return to work when, clear the conntrack to the server IP

did u disable sip 5060/5061 at Service-Port?