I've had this router for a couple of years and no issues with it overall. It does a good job now but I would like to see faster wifi speeds if possible. I understand that distance also plays a role in wifi performance.
Been looking at reviews and many of the newer routers have MU-MIMO. We dropped cable a while ago so we stream using AppleTV throughout the house as well.
Any suggestions would be appreciated.
That router is still fine, I would consider adding an AP or two (or cheap AC routers configured as an AP) if you are having signal issues in distant areas. I'm up to 5 APs in my pretty big house/guest house and basic early AC is still my go to equipment.
You could consider upgrading to an AC downlink MU-MIMO model, but that wouldn't get you nearly the advantage you hope, relative to more APs. 5GHz just doesn't have the distance due to its greater absorption by matter, walls, air, even glass and window tinting.
The newest AX routers are not really going to give you better distance, but for capable devices they will support more devices at better speed -- but only if the devices also support the AX standards. Personally, I am holding off on considering AX for a while, until more of the issues are worked out with the many newer additions.