My router placement in my condo is just 1 feet away from where my sofa is so pretty sure that's the sweetest spot in the house

Tried fidgeting with the channels, upgraded to the latest firmware available, reset and reconfigured the router but the results are the same. On the current Time 100Mbps line, I am only able to achieve around 40+Mbps on wifi but can hit 80-90+ Mbps on LAN. Since the fibre was pulled all the way to my modem and not the last-mile-copper types, that rules out any cabling issues considering my speed on LAN is very much acceptable.
Of course I tried my luck emailing Time Support and complained about the Linksys E1200 router they gave me 2 years ago. Here's their response:
"Please be inform that the given Cisco Linksys E1200 router is run on 2.4Ghz radio frequency band which can support up to 40Mbps on WiFi. We regret to inform that we do not offer any router replacement. You may purchase the dual band router on your own or purchase the router from TIME through our selfcare portal."
So all things considered, does this mean I really need to get a new router to hit the promised land of 100Mbps and stop flogging the old E1200?
Checked the official link here:
http://www.linksys.com/my/p/P-E1200/Still find it hard to accept the E1200 can only support up to 40Mbps on WiFi.
Just buy a new AC dual band router.