Question about AVM FRITZ!repeater 3000 WLAN Mesh International / CH

Yes, it is possible, but I would generally only recommend a mesh WiFi system to improve the WLAN, which achieves much better coverage.

The Xiaomi AX3000 mesh system, for example, consists of two identical mesh WiFi routers, switch off the WiFi on the Wingo router, connect a Xiaomi mesh router to the Wingo router with the LAN cable and then set up the WiFi mesh on the smartphone. This gives you very good coverage, as two mesh routers create the WLAN at the same time. Both are very powerful and can manage up to 256 devices and each has a built-in 3 port Gbit Ethernet switch, where you can then use a server or printer with it.

Xiaomi AX3000

Operating a separate router together with the Wingo WLAN is a technical mess.