@floridafan19
When you say "can't connect to any device", do you mean just your Roku devices? Also, is this a single device (by modem, do you mean a modem/router or is the modem seperate from your router)?
No matter the Roku device, you should be able to connect to the 2.4ghz band at least. From within the new router, make sure the 2.4ghz radio is enabled and broadcasting and that you are using a wireless channel between 1 and 11 (not Auto).
Additionally, you can try using the network connection reset from within Roku. (Settings. System..Advanced System Settings..Network Connection Reset...Reset Connection
Also, verify that you have unplugged your old modem/router and it is no longer in use.
Post back with router model number and Roku model numbers if need more help.
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