Cannot access 2wire network and/or signal is poor

I have a 2wire router from A&TT
Model is 3800HGV-B

We have a problem with the wireless network(the wire connection works fine).
Sometimes I can see the network and it says signal streng
ht poor. Other times I cannot see the network at all. I can always see neighbours wireless networks.

The wireless network has worked pretty well for a couple of years so this is something new.