Mate I’m genuinely not trying to be an ass with this but does your plan specifically include mobile hotspot usage?
T-Mobile has dozens and dozens of different plans from the last decade alone, it’s quite possible your plan has zero hotspot data. Especially as you mention it’s an older grandfathered plan.
I’m also pretty sure they’re allowed to modify old plans, like removing support for hotspots, to try to force people onto new plans. AT&T at least has some boilerplate language that allows them to modify your plans.
Mate I’m genuinely not trying to be an ass with this but does your plan specifically include mobile hotspot usage?
T-Mobile has dozens and dozens of different plans from the last decade alone, it’s quite possible your plan has zero hotspot data. Especially as you mention it’s an older grandfathered plan.
I’m also pretty sure they’re allowed to modify old plans, like removing support for hotspots, to try to force people onto new plans. AT&T at least has some boilerplate language that allows them to modify your plans.