Can't connect to network on new android from C6220 cable modem router

[ForrestG]

Bought brand new phone & I can't get it connected to the 5G network on the cable modem router. My old device works just fine but the new just won't do it. And it is dual band too. Thank you!!

[plemans]

What error are you getting from the phone? 

Any special characters/spaces in the ssid/password of the router?