@David-TP I can confirm, that the Telekom must have done something on their side. VOIP with my VR600 V2 is working now, even with the non beta firmware VR600v(DE)_V2_220113.

Same problem here with my VR600V V2 and Telekom VOIP. As far as I have read in the forum, other tp-link devices are affected by the same problem. And Telekom seems to point to tp-link, so they have...