Also, an FYI for anyone on the IIJMio eSIM plan:
There's two tiers of throttling. Once you use up all your high-speed data you get throttled down to 200k. But if you manage to use 366MB of data in 3 days while throttled, it gets throttled down even more to a speed that's "not public" but has caused my phone to think it's not connected to the internet at all at times.