According to the information provided by GL.iNet Staff, it’s possible to connect a GL.iNet router (such as the AR750 or AR750s) to an Xfinity hotspot, but you need to make sure that the ““DNS rebind protection”” is turned off. It appears that the router will then prompt you to enter a username and password, and if you are still prompted to install a certificate, it might be worth checking out this article on Multitechverse, that might give you more information on how to troubleshoot this issue and provide more steps to connect your router to a protected Xfinity hotspot.
Keep in mind that different routers may have different configurations settings, so it’s important to consult the instructions manual or the support site of your router before proceeding. I hope this helps, and good luck with your connection!
Xfinity has two SSID’s that it uses. There is xfinitywifi and XFINITY. The lowercase one is meant to be used with a username and password. The all caps one is meant to be used with a certificate. One can download the Xfinity hotspot app and sign into their account on the app. The app gets the certificate and will then automatically sign into the all caps SSID. Likewise, if you are a subscriber to Xfinity cellular your phone will come with the certificate pre loaded so the phone automatically will connect to the all caps SSID.
Tldr, you need to use the all lowercase SSID with your GL-iNet router.