Running a Jellyfin server when I don't control IPs

I don’t know if this is the right place, I don’t even know if this will post but I had a Jellyfin server setup with a router and static IPs however with my ISP supplied router I have to use my router as an AP or I’m double natted, no IPV6, the dumb thing is that I can’t set IPs static on ISP router. There’s got to be a...