User interface FritzBox despite internet connection not available. What to do?

I scoured many forums and posts but came to no solution. The user interface of my Fritzbox can't be opened from my PC. However, I can surf the Internet quite normally.

My network consists of a Fritz box 7490 and two mesh repeaters (Fritz 1750E). Because of the long distance my PC (via LAN) hangs on the second repeater, which reinforces the first repeater via a WLAN bridge. Network is completely set up as a mesh. From my PC I come neither on the user surface of the Fritzbox, nor on the repeater, nor can I control my home network printer. The only thing that works is the Notfallip 169.254.1.1 with which I can access the repeater, where I'm connected to LAN… And the Internet works fine (just write the question about the PC).

The funny thing is that when I connect, for example, my laptop with LAN, access to the Fritzbox interface and repeater works fine.

I have already emptied the cashe, my PC on visible in the home network, anti-virus and firewall programs paused, the IPv4 settings checked (automatic IP), but nothing works. There must be an error with my PC somewhere.

Win10 Home, 16GB Memory, Intel (R) Core (TM) i7-7700K CPU @ 4.20GHz Processor)

Can anybody help me further?

Thanks & Greetings

Domi

How do you call the Fritzbox via browser?

IP address or fritz.box?

Both as well, both are not working. IP address 192.168.2.1 works from the phone and laptop. About Ipconfig I also see that the default gateway is 192.168.2.1.