Devices not connecting to the 5G band on the XR500

[Adrian126]

Hello,

I changed my ISP modem yesterday, I have a spectrum cable connection. They gave me a ET2251 technicolor modem. I went through an extensive process in getting it set up, had to call and everything, but I was eventually able to connect it to my nighthawk router that I've had for about 2 years now. The only problem I'm having is that the 5G band won't work. Devices are able to find the SSID, and the router light for the 5G band is on, but nothing can connect. Smart phones stay connecting endlessly, and laptops connect and show no internet. The 5G is being displayed as connected in the OS settings as well, but I don't see the band in device manager.

I have MU-MIMO on, and HT160 off. I've tried several reboots, with these options on and off. The 5G band is using channel 153, which it has been using. The lights on the router for both the 5G and 2.4G flicker consistently, but the 2.4 gives no issues, both lights have been that way since I got the router. I haven't tried a factory reset, and the firmware is up to date as well. A guest network 5G band seems to work just fine, so I'm not sure what the problem is with the main one.

One important thing to note, is that the ISP modem came with a router that used a smart connect system, so maybe there's a possibility that the 5G band isn't compatible with the modem, but Spectrum told me that wasn't the case. Also, If I change the router to smart connect, my devices aren't able to connect to the router at all.

I've run out of ideas, so I'd appreciate any help that anyone can give me. Thanks in advance

[plemans]

I'd try the factory reset option to start with. 

[Netduma-Fraser]

Try a reset as above first, if that doesn't work then in Advanced Wireless settings, disable the wifi radios fully, then apply, then reboot the router from the interface and then wait 2 minutes then enable the wifi again then apply, then reboot and see if it works properly then.