I can only guess the connectivity between your mast and the Internet is awfully congested, and/or you are in the middle of nowhere.
One of the reasons starlink does as well as it does is the ground stations are well connected to the wider world, whereas your nearest cell mast might not be.
I'm not joking: https://www.pcmag.com/news/is-starlink-good-for-gaming-we-pu...
Are you doing the 113 test from the actual device, or something tethered to it? For example, you don't want a bluetooth stack in the middle.