Default Connectify-like networks stopped working

Hey guys!

Few weeks ago I debranded my HTC One and flashed stock international and my wifi is not behaving as it should anymore. The phone connects to my Connectify network but loses that connection after a minute or so (even though it shows as still connected pages will not load etc). It works flawlessly if it's directly connected to any wifi, but if I try to make the same wifi(or any cable network) shared with programs such as Connectify (pro) or Mhotspot it doesn't work.
My other phone, Sensation, and a laptop both work fine on the same Connectify network.

I reflashed multiple custom roms/stock many times, went back with nandroid backup to original system, did factory resets and nothing helps now.
I also reinstalled windows on my PC and installed all newest drivers.
Found a lot of posts about similar issues, none with a working solution though.

Phone currently is on stock 4.4.2, 4.19.401.8. Radio 4A.23.3263.28_10.38r.1157.04L. It's a PN07100 model.

Any ideas? I got no wifi on my phone for over 2 weeks now, so I'm begging for help. Any suggestions what might be causing the problem or could be involved?