Mobile hotspot LAN only?

Right, so I’m a bit frustrated, I tried playing using my mobile hotspot but it only lets me play LAN?! Every multiplayer game I play works fine except this one and I usually get a latency of 30-50ms. It goes online while I use my wifi, but it’s being used by other people so I get a latency of 500-800ms with it, so I’d prefer to use my mobile internet. Can someone tell me what I’m doing wrong please ?!