Hi Leon,
using each remote control - can you go to:
menu
signal information
and tell us the
strength and quality figures for both TVs -
for when the signals for both are good,
and also when the "weather" causes them to drop out on one TV?
Also -
try using the bad TV without the splitter:
https://www.theantennacompany.com.au...ing-3-x-rg6-f/
cheers
Allan