looking to separate bands on Xb8

This may or may not apply anymore as a lot of features / functionality have / has been disabled.. YMMV.

If you are not using any Xfi Pods, you can try separating the combined 2.4 and the 5.0 bands and give them two different broadcast names / SSID's;

https://www.xfinity.com/support/articles/change-wifi-mode-admin-tool-xfinity-xfi  

Hey there, @user_h8e9rt! As our awesome expert, @EG, pointed out, a lot of those features have been disabled, however, following the instructions in the link they provided will allow you to disable band steering and separate the bands. Let us know if that worked for you.