I currently have an ARRIS SurfBoard SBG6900-AC modem/router with 250mpbs service through Xfinity. The WiFi router aspect of it does not work well (ethernet works fine), even after numerous calls to Xfinity and Arris. Since I can’t find a solution to make it work, I’m going to get a new WiFi router to connect to the modem and disable the WiFi radios on the Arris. I don’t think I’m looking to get a new modem or combo unit.
I am wondering if anyone has recommendations for routers that would work best for my situation. I live in a small 1400 sqft condo that's two stories, so not a lot of area to cover. We do not have cable, but rather we stream all of our tv, and we can have up to three tv’s streaming at a time. Here's a list of devices we usually have connected to our network: (1) Sharp smart tv, (1) smart BluRay Player, (1) Xbox 360, (1) Tablo OTA DVR unit, (1) Google Home, (1) HP Wireless Printer, (2) Roku Expresses, (1) Roku 2, (1) Roku TV, (4) iPhones, (1) iPad, (1) Desktop computer, (1) MacBook. So a lot of devices overall with a heavy emphasis on multi-device streaming. Indeed, not all of these are active at the same time, but we can have up to three tv's streaming at a time.
Does the ACxxxx number make a difference if my internet speed is only so fast? Would I see a benefit from getting an “AC2600” vs. “AC1900” router?
I’m looking at the Linksys EA8500, or the Netgear Nighthawk series...AC1900, X4, or X6 but I don't know if those would be overkill
Any recommendations or ideas are much appreciated!

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