I just don’t know why ISP’s in general & particularly the big ones insist on providing junk routers. Not all routers are created equal, & by delivering sub-standard equipment to their customers, they’re inflicting below-par performance on unsuspecting users.
The quickest/easiest browser-based speed test available is at fast.com. Go there, compare your result with what you’re paying for. If your connection doesn’t compare well – especially if you’ve got UFB – invest in a brand-name router. Linksys, Cisco, Belkin, something like that. Recently I took a shaky, unreliable 12MB/s connection to 27MB/s stable just by changing the no-brand router to Ubiqiti.