Yesterday both of my rokus displayed not connected. I began a set up connection, and they both had the green check mark for wireless connection. They failed for the internet connection. I then called my internet provider T-Mobile Alcatel Hotspot. They had me do a reset on my hotspot and a reset on my rokus. Neither of these helped my situation. He then had me change my password which didn't help either. I also, unplugged my roku and still nothing.
Some Roku devices have an issue when the router or hotspot uses a password that contains special characters or is too lengthy.
If you cannot leave the password field empty, then try an easier password containing only numbers and letters and minimum required. (Can also see if you can try an old default industry standard 5544332211).
I know your provider already asked you to change password, but usually the only two things affecting hotspot connections are band selection and password.
Otherwise, alternative is to see if your Premiere can connect to an alternate network (friend, family, etc). If not, then may start considering possible device failure.
However, since you have two behaving in same manner, seems like it is more likely to be a network or password issue.
Roku Community Streaming Expert Just another Roku user... I am not a Roku employee. Insignia RokuTV, Ultra 4660, Premiere+ 3921, Express 4k+ 3941, Streambar 9102