Dear Old friend,
I am using the same
router for an year.
My observations:
LAN speed are always full. Hence, not the problem with ISP.
WiFi speeds are always less. By how much, that's where the specifications of the router and client device come into picture.
Few things, I have tried(I know you are already a pro):
Update/re-install WiFi drivers at old
laptop/pc.
Newer laptop always get higher speed connection. Seems to have better hardware.
Played with router location to get better speed at important location in the house.
Played with antenna directions to get better speed at important location in the house.
Played with laptop placement and direction in the room to avoid blind spots.
Played with different WiFi bands/width to avoid network interference with the neighbours.
I managed to get maximum 94mbps up and down on an 100mbps connection at few places in the home. Not all the devices and not all the locations get that speed.
The only problem still bothers me is the quality of
DNS. Downloads are blazing fast. Browsing is damn slow, similar to old 512kbps or 1mbps era.