I just got this router today.  I had it set up in just a few minutes and was please with how easily everything went.  I connected with two phones and a laptop wirelessly, and an additional wired connections.

I then tried to connect a Roku device.  The Roku could see the SSID, would ask to input the password but would not connect.

While I kept trying and retrying my password, one of the phones (Redmi Note 8 running Android 9) I had connected started doing the same.  It could still see the network but would no longer connect.  I never received any error messages or prompts for passwords; I just could not connect to the wifi.

I eventually got around the error (temporarily?) by creating a guest network.  My phone and the Roku connect to this no problem.

The host network still functions for my wife's phone ( iPhone 8+).

My phone can still see the host network, but my phone cannot connect to it.

I don't like the use of the guest network and would like to get everything functioning properly on the host network.

Things I've tried:

1) Restarted everything multiple times

2) Switched to AES Encryption

3) Changed the password to only alphanumeric characters (a solution recommended in a Roku forum)

4) MAC filtering is disabled