Range extender 3700 password problem ,

The 3700 extender worked fine at my old house ,

New house has broadband fibre ,, the range extender connects OK to main broadband router , but when trying to connect other equipment to 3700 range extender , it wont accept main router password.

I have done factory reset and mywifiext logins several times it goes through the motions the 3rd light goes green for 5 seconds and then I get message , ''password not correct '' or ''cannot connect to this network''