Software issues with router?

I have been a loyal Comcast/Xfinity customer for over 20 years.
Recently, I have noticed that my Xfinity provided router stopped giving out the 5Ghz signal. I have the Xfinity app and everything. Which let's you restart.

After some research, I have noticed that some other customers have experienced similar things, with the 5 Ghz range dropping out.

I did actually try separating the network id's (it says not recommended), and appended 5Ghz to the SSID.

To my current knowledge, I haven't changed more than that. I'm wondering if there was a software update? There might be a word for this - is it bandwidth spreading? I think I like the idea behind Xfinity having the technology to connect to devices at 2.5 or 5, it's just that if it breaks, I need a way to reach out.
I thought I was a "normal" use residential customer. 
Should I push to get my Xfinity gateway replaced?