Iphone tethering always stops working after successfully watching a youtube video and then browsing the web

Problem seems to be solved now, after updating to ios 12.5.1, and also installing a recommended Network Service Provider update from Apple, which were all done on i-tunes.

Differences noted:

Old speed = 2.55 Mbps (1192 ms ping)

New speed= 24.43 Mbps (23 ms ping)

Before update: Phone was hot to touch during tethering

After update: Phone remains cool during tethering

Same problem with previous network provider, and this issue appears with my current new provider, which I thought would solve.

The previous provider had support technicians working on the issue but to no avail.