I have a client who has a comcast business connection (cable 50/20), with Comcast's cable modem acting as the firewall/router for the internal network (7 people). Their PBX is FreePBX, hosted offsite as a VPS. All of their phones are able to make outbound calls. 2 of their phones, keep losing registration with the server, so when calls come in to the incoming queue/ring group, those 2 phones do not ring, because FreePBX has marked them as unreachable. Has anyone had any issues similar to this? I've already factory reset the phones, and removed and re-added the problem extensions to rule out a misconfiguration. Still experiencing the same issues where the phones register, then unregister.