@Clive_A no-address mode has fixed the problem. However, I am sure I have already tested every option beforehand. I can't say exactly what made the difference now. Thank you.

@Clive_A Hi Clive, thanks for your response, but no, the provider device is running in bridge mode. If I use in AVM router instead of the ER707, also behind the bridged provider modem it is getting a...

Hello everyone, I'm having an issue where my TP-Link ER707-M2, located behind a Vodafone Station in bridge mode, is not receiving an IPv6 prefix. When I use a Fritz!Box instead of the ER707,...