How to buy UPS!

I moved into a new apartment about two weeks ago. And I noticed very strange problem with my tv-avr-pc setup. When we turn on/off lights my screen loses HDMI signal for one second and then it comes back. It doesn’t matter which room which light, almost everything related with electric effects and HDMI loses signal.

First step: I searched what might be the reason, and there was two options; bad HDMI cable and old electric systems. I thought it can’t be HDMI cable problems because I was using same cables before and nothing happened. Second option electric problems, it was more realistic because this apartment is a bit old! I found an UPS with surge protection for my TV , AVR and TV. It was a small slim box but unexpectedly heavy, Anyway I was very tired when I brought it home finally. Started to test very excitedly , first surge protection; everything is still same. Then I connected all devices to my UPS and disconnected from home electric but still I had the same problem, it was very surprising for me, because I couldn’t understand it!

Second step: I thought if it is not related with my home electric ,it must be HDMI cables. I have two HDMI cables, one is 10m from aliexpress and other one is 2m from Fujitsu. Before my aliexpress cable was connected TV to AVR and Fujitsu was connected PC to AVR. After moving I changed them because I needed longer cable between PC and AVR. So it was my mistake! That stupid cable was effected from everything. After changing them back problem solved but I have already bought that new UPS.

Now I have Eaton 5S 1000i UPS 

I am using for fun, because in this city electric is very stable we don’t have problems but I am open to new ideas!

If something is broken check everything and then go and buy new solution. Don’t be hasty!