Hi,

this is a translated copy of my post in the german section. Maybe I get an answer in English.

My internet provider is netcom-kassel.

Internet works (DS-Lite) like charm, but the sip-connection only works after restarting the router or if making changes in the phone number settings and press the save button.

After the forced connection break every 24 hours by the ISP or a short DSL drop, there is no successful reconnect to the SIP-server.

logged error: error 503 (service unavailable)

There are many attempts to register the phone number in the log with the same error message.

Registrar: netcomcity.de.

Connection to sip-server via IPv4.

Error 503 means DNS-problems or phone number registered twice.

For DNS the netcom-DNS is used. So shouldn't be the problem.

I guess the VR600v tries to register the phone number without dereregistering first. So for the sip-server it's a not allowed second registering.

For Fritzboxes there is a config manual at netcom-kassel:

https://cdn.marketing-cloud.io/wp-content/netcom_kassel/uploads/2021/07/14112648/anleitung_telefonie-nc_v15_2021_07.pdf

But that doesn't help that much for a TP-Link router.

I set the router to restart every three days. Now it works only every three day for one.

But that's not an optimal setting. So I need help for a real solution.

Update: I recently added an old Samsung SMT-G3010 as client to the VR600v and configured the phone number.

Works for many days now without problems! In the log of the SMT-G3010 is shown that the connection was deregistrated before reconnecting "Deregistiererung Rufnummer 0049xxxxx"!

That seems to lack at the VR600v...

Even if it works right now this way, I'd like to get an updated Firmware.