My phone suddenly doesn’t load data in LTE mode, only in 3G

I have an iPhone X and for the past few months the cellular data is working fine. Then a few days ago my phone suddenly won’t load data even when the bar says it’s in LTE. Every time I use it, it keeps turning on the location and the page or app I’m on won’t load at all. My location is covered by LTE. I recently discovered that I could load data, but ONLY if I manually switch the network to 3G. When I try to switch back to LTE, the internet won’t load again. I’ve tried turning airplane mode on and off, restarting the phone again and again, taking out the sim and reinserting it, and resetting network settings, but so far no dice. Have any of you experienced the same thing? What can I do to remedy this? I don’t want my phone to be stuck in 3G.