Going from Bad to Worse - Time Warner Internet

This question is about "Going from Bad to Worse", with Time Warner Cable internet and apps. Just had my UBEE combo unit replaced with a separate modem and router. I was given a Sagemcom FAST 5260 router. I am seeing poor speeds for the 2.4 channel as compared to the UBEE.

Any recommendations on a good router from the list that Spectrum offers or from the approved list?

Primarily my most important requirement is for 4K movie streaming on my TV over the 5GHz band, or the 2.4 band if I can get adequate speeds. I wasn't seeing even good DSL speeds when streaming with the FAST 5260 router to one of my other TVs on the 2.4 band. I was at least getting about 5Mbps with the UBEE. I couldn't even get 1080 resolution with Netflix using the Sagemcom Fast 5260.

Going from Bad to Worse?