VoIP dropping calls (go silent on both ends, but still look connected)
We have an M470 (12.7.2) setup with a VoIP VLAN, using 8x8.com as our VoIP provider and using Polycom vvx310 and vvx311 phones. They have worked great for years. Now we have calls drop (go silent on both ends, but still look connected) randomly throughout the day. The drops do not appear to impact multiple users at a time. There are only about 6 people in the office regularly. There is a an AltaFiber Fiber 1000/250 Gbps connection. I monitor the connection from time to time and do not see any outbound denials from the VoIP VLAN. I do have fairy detailed policies to allow and optimize VoIP traffic and taking this link into account https://support.8x8.com/cloud-phone-service/voice/network-setup-voice/x-series-technical-requirements. As a troubleshooting measure, I have allowed all outbound traffic from the VoIP VLAN. It does not seem to help. Could it be some kind of obscure timeout or global networking setting? Please let me know your thoughts and suggestions. thx.