The wireless module suddenly started to fail. What to do?

Question

iMac

iMac 21" worked absolutely fine.
One fine day my WiFi router died (iMac was not connected to the network or power supply at that time
).
At the same time, the signal from the new router, when it stands next to it, finds it in both ranges.If you take the router to another room, the signals are
lost.It is even more interesting with bluetooth - it finds devices (including neighbors), but cannot access them (mine)
connect.Moreover, when connecting various external adapters, both WiFi and bluetooth, via USB, it recognizes them, but shows them as non-working (drivers installed from the manufacturer ("Mojave"), did not help)

The next step:
On the computer it is in the bootcamp of wines 10. The
built-in WiFi / bluetooth is detected, but it works exactly the same as under the macos.

But external modules plow without any problems.

I can’t open the aimak, it’s troublesome and expensive to go to the service (he was there quite often anyway).
Therefore, before the service, I would like to find other possible solutions.
Confuses the synchronism of the failure of the router and the wireless module.