@criexe 

I would try the latest AX55 firmware to see if that fixes the issue.  The firmware may be found here.  It's only available on the TW site for now and it works for all regional versions (US/EU/etc) of the AX55.

  @jra11500 

thank you for the advice, i wasn't aware of a new version, i'll give it a try

  @criexe Hi, I have the same problem. If you find a solution, please help me.

  @jra11500 tested the new firmware and no luck.

it's a shame, this issue is well known across all forum and to link itself and they just ignore it 

  @criexe 

I'm sorry to hear the upgraded firmware did not fix your issue.  Here I have 3 iPhones (2 iPhone8 and 1 iPhone5) and they haven't experienced any issues since last year.  I realize that these are older iPhone models and only feature an 802.11ac interface.

If your devices are newer models, have you tried changing the Mode setting under Advanced, Wireless, and each band's advanced settings to exclude the "ax" option?  That's not a fix but it might help in isolating the problem.

  @jra11500 

already tried, no luck

some people told me to completely disable the 5ghz WiFi network, I didn't want to lose 5ghz WiFi but I'll give it a try

So I tried to set up a guest network, I'll use that for few days and I want to see if I have connection losses 

  @Yasser-S 

do you have spaces in your SSID?