Hello,
Thank you for reaching out.
Could you please share screenshots of both your FRITZ!Box and Teltonika WireGuard configurations?
There was a similar topic discussed recently where there was an almost identical VPN setup between a Teltonika router and a FritzBox was successfully implemented practically. You can check it here:
It might help pinpoint what’s missing in your case.
Additionally, there’s a Teltonika & FRITZ!Box WireGuard configuration example available here: FritzBox and Teltonika WireGuard Configuration example - Teltonika Networks Wiki
that may provide useful insights and instructions for your specific scenario.
Best regards,