WNDR4500v1 runs slow for all wifi-connected Android Devices within 24hrs

Hmm.. that's sorta not what I wanted to hear but the 4500 is ~4-5years old and we got some good mileage out of it. I wanted to wait on the next wireless standard to supersede AC but I can easily afford a new high-end router if necessary but its a toss-up between Asus and Netgear as both get exceptional reviews. Do I want the elite-end AC5300 (Nighthawk R8500 X8) or AC3200 (Nighthawk R8000 X6 which is now almost 2 years old but leads the Router charts in that AC category). As mentioned, I wanted to wait for the next Wifi standard to replace AC (which is on the way) but the situation with the Android devices is becoming absurd.