I use it all over the western half of the USA. I’d say maybe 10-15 percent of locations where I have signal the actual speeds are abysmal. I think due to the mvno data being deprioritized but I can’t say for sure. I still keep them because it’s cheap but it can get annoying
No advice on a new one, sorry. But if you decide you want to get rid of your current one cheap let me know :)