I use AIS and if i tether to my tablet it works briefly then loses the internet connection or internet drops off. Happens on YouTube as well as another couple apps so it's definitely a connection issue.

 

I have an unlimited monthly package, should work

Sorry to ask, but have you tried to use these apps on your phone, just to prove that the issue stems from tethering?

My daughter showed me how to do this off her phone with AIS. Powered my laptop and the TV during a day when our wifi didn't work. 

Just be aware that tethering/hotspotting realy eats away at your battery!

55 minutes ago, Boomer6969 said:

Sorry to ask, but have you tried to use these apps on your phone, just to prove that the issue stems from tethering?

until today I've been using the same apps on my tablet with a data sim which just run out. It's using a wifi hotspot is the problem, maybe a tablet issue, not tried before

I have unlimited AIS sim. Works perfectly tether anything, hours and hours, yes sure it kills your battery on the sim phone . No worries 

1 hour ago, DezLez said:

Just be aware that tethering/hotspotting realy eats away at your battery!

Yep, and @scubascuba3phone may go into low battery mode, hence apparent limitations on data.

I also had problem with high packet loss while tethering from my phone with a DTAC SIM card, but only after a while.
I ended up using a 4G LTE WiFi dongle that's much more stable.

https://www.cnx-software.com/2021/08/21/review-of-4g-lte-wifi-modem-hotspot/

I solved the issue i was having which was constantly disconnecting from my Redmi Note 9 hotspot. I had to reset wifi, mobile data and bluetooth in Settings, Connection & Sharing. Seems it's a known Redmi issue sometimes