The Linksys is working perfectly fine. I have no issues with that.
Linksys (5GHz) -> R6220 -> Phone (5GHz)
The above is intermittent
Linksys (5GHz) -> R6220 -> Phone (2.4GHz)
Linksys (2.4GHz) -> R6220 -> Phone (5GHz)
Both above are slow.
I've been able to cause intermittent wireless with just using the R6220 and adding multiple access points to it and connecting the phone to one of them. Without the Linksys being in the equation. I thought it may be a DHCP conflict but I don't know now.
The Linksys is Marvell.