Remove utguest so it does not rejoin in macOS
go to the apple menu
select system preferences
select Network on about the 4th row if you're counting the appleid portion as a row.
unlock with eid-admin on lower left of pane
click wifi
click advanced
click utguest
click the minus sign in the lower left
while you are in this pane, find utexas in the wifi list and drag it all the way to the 1st or 2nd position just above or below your home wifi network. you can do the same with your home wifi.
make sure the auto-join is checked off in both of those networks. doing these last 2 steps will take less "cycling" time through all the wifi networks to rejoin when home or back on campus
you may take this opportunity to clean up all the old wifis you might have joined in your travels and select them and click the minus sign here too.
click ok and close out of the preferences.
if you "fall off" of utexas, it may add utguest back