New Router, Roku thinks the secure network is unsecure and won't connect.
I just installed a new router (ASUS RT-AX86U). I used the same SSID and password as the old router and every other device in the house had no problem connecting to the new router except for the Roku Express 4K+ 2021. The Roku displays the network in the list but it shows as unsecure (no padlock icon) even though the network is secured with the same WPA2-Personal authentication as the old router. All other devices see the network as secured. The Roku attempts and fails to connect to the network without requesting a password. I have rebooted all equipment and even factory reset the Roku, still no joy. Out of curiosity, I created a secure guest network on the new router and the Roku shows it as secure and can connect once the password is entered. Why doesn't the Roku see the original network correctly?
There is a known issue with Roku devices and Asus routers not authenticating/accepting passwords. Roku has indicated that it will be releasing a fix in a future build update. (Your guess is at good as mine when this will occur - apparently it is a secret).
For the time being, you have discovered the workaround with creating a guest network. (For some Asus routers, the password has to be disabled on the guest network as well so you are currently in a better position with being able to use a password.)
If I hear something, I will update try and update this thread for you. Otherwise, since OS 11 is now beginning to roll out, try again when you receive the new OS update. (it could even be in a future build number, so may not necessarily hit with the initial release of OS 11).
Edited: Another workaround used to be disabling "Airtime Fairness" on older Asus routers, but does not seem to fix this issue with the newer wifi6 routers. (may be worth a shot).
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