Sounds like you cheaped out to be honest, either cheap modem or cheap plan. Or bad coverage in bumfuck town.Those "pocket wifi" things have always been sketchy. Mobile internet speeds without the mobile device optimization. One time after a move I tried using one since it was going to be a couple weeks before the phone people could get me a proper DSL connection and I ended up taking it back to the store after two days because it was much worse than just going to a coffee shop or library. I can't even vaguely imagine trying to stream at a professional level using one.
Fauna's sister is really getting the famous mama buff