Why are connections dropping?

Question

Computer networks

PC under Windows 10, Beeline smartphone as a USB modem. In Windows, TTL=65 is registered, because the tariff prohibits the distribution of the Internet.
Everything worked ok, but a couple of weeks ago the connection became terrible. Pages in the browser open for a hell of a long time and 2 times out of 3 they simply fall off "unable to establish a connection". At the same time, 2ip (when it boots up :)) shows quite normal speeds of 8Mbps down and 2Mbps up. FTP via FileZilla works better too. And it is worth noting that if you already launched a video on youtube, then it normally goes without lags.
What could be the problem? At my amateur level of understanding, these are some problems either with DNS or with establishing an http connection.

Answer 1

My car is running bad - sometimes it goes well, sometimes worse. When you roll down a hill - finally there are no problems. Who can tell what could be wrong? Approximately such a question turned out)) Diagnostics is akin to wiping the glass, knocking on the wheels))
Statistics on pings at least. As a result, do you distribute the Internet to the network, or do you use it only on 1 device? If you distribute - at all places of the brake? Have you tried different browsers? What browser add-ons are installed? Etc. - at least start with this.

Answer 2

What does netstat say?

Answer 3

Try to monitor the network using third-party software.