Well, as it turns out, I got the IPSec-connection finally running with a dynamic-DNS name mapped to the TP-Link-Router (using the tplinkdns service in this case) and using that name as the FQDN on...

@Sunshine Hello, thank you very much for your reach out and support offer. Hi, may I have a screenshot of your IPSec VPN Settings on the MR6400 and also the FRITZ!Box? Sure! Note that the FRITZ!Box...

Hello, I have issues with a TL-MR6400 router, which I'd like to use for VPN. The problem I have is EXACTLY the same as described here: https://community.tp-link.com/en/home/forum/topic/99462 (TL;DR:...