I can't connect my hp envy 4502 to my network. I have read about changing security from WPA3 to WPA2 but I don't know how to do it

I'm not really sure if this works anymore...... YMMV. 

It cannot be done via gateway (10.0.0.1) itself, but via the XFinity App  (although it is a bit hidden): Go to XFinity App, select 'connect' on bottom, select the network name, 'view/edit WiFi Settings', change security mode to WPA2.   (WPA3-transition doesn't work either). 

Go to the Xfinity app 

Select "connect" at bottom of screen

Select "View or edit WiFi settings"

If you have split the bands by assigning a separate ID and Password for each band, then select the 2.4 GHz WiFi band 

Go to the Security Mode box where if may say "WPA3 or WPA3-Personal-Transition" and change to "WPA2"

Then "Save"

Then redo the HP configuration wizard - it hopefully will work.

https://www.xfinity.com/support/articles/change-wifi-security-mode 

Good luck !