phone not connecting when on another (vpn connected) subnet

[GVB]

Can you just tell me which ports are used for the registering?

Is this the 5000/5001 combo or 5060?

 

[eddv123]

5060 is standard SIP registration, since you are using VPN and the traffic is seen as "local".

Https - 5001 is for provisioning normally external endpoints so for local provisioning you are normally looking at port 5000. https://www.3cx.com/docs/ports/ if you have kept everything as default.

 

[GVB]

things were acting strange here and disabling nat, excluding from nat and firewall rules didn't seem to solve anything.

after a reboot of the router the phone registered!

it seems that the router was freaking out on this for some reason.