Why did TeamViewer start to slow down over wifi, but it works correctly over mobile Internet?

Question

Computer networks

Hello!
I am in Thailand on computer A, I have been working with computer B in Russia using teamviewer for more than a year.
And it is not known why teamviewer started to slow down a lot. Some kind of network problem on my side.
Since when changing the network to mobile Internet (I distribute it from a smartphone), the teamviewer flies.
The same is observed if instead of computer A I use another computer B (wifi - teamviewer slows down, mobile Internet - flies).
1. OS on computers A and B are different
2. I didn’t touch the network for a long time (didn’t change the settings)
3. teamviewer didn’t update
4. Judging by speedtest.net, the wifi quality is the same (exactly the same as the whole year)
Where to dig?
Of course, I can call dancers from the Internet provider company, but this is ineffective, since it is difficult to convey the essence of the problem to them.
Thanks

Answer 1

The Internet does not fall off when wi-fi is connected? Maybe there are more points nearby that operate on this channel, at this frequency, or other emitters of radio waves interfere? Noisy air is a sad thing.