Screen mirroring question.

I have an iPhone 8 SE 2020 and just got a Samsung Smart TV. I got screen mirroring to work, but the TV and iPhone have to be connected to the same Wi-Fi network. Because the iPhone is connected to Wi-Fi, it then uses the Wi-Fi to connect to the internet while screen mirroring. The problem is my Wi-Fi is slow, 3 MbPS. That’s OK because I never did any streaming, just email, Facebook, and other things that don’t require high speed. My iPhone uses 4G LTE and is around 50 MbPS with unlimited usage. Is there some way to have both devices connected on the same network, but still let the iPhone use 4G LTE to connect to the internet instead of using the slower Wi-Fi .