Not sure exactly what you are saying, there was a lot to unpack in your post. Your WiFi signal strength is Ok provided it is also stable. I
You say you have tried the Brennan in another house and the problem persists? Please explain or confirm further this is important.
Please
1) try your WiFi dongle in the other Brennan USB port.
2) if this does not work please try an connect the B2 using Ethernet
3) try rebooting your router.
Please get back to us with progress..
Fred