How to obtain fast ping times and download speeds?

I'm replacing a friend's old Belkin N150 WiFi router (10+ year old technology) with a new Arris SBR-AC1750. The old router does not deliver sufficient throughput when multiple devices are connected, and does not support his 802.11ac devices at full speed.

We connected his Windows 7 laptop that uses an Atheros AR956x Wireless Network Adapter (802.11b/g/n) to the router, and nothing else.

The laptop does not see the 5 GHz SSID, so I'm guessing that chipset does not support 5 GHz. (Please correct me if I'm mistaken. Maybe there is somewhere to turn on 5 GHz? Nothing obvious in Device Manager's Advanced Settings... just "AdHoc 11n", which is something completely different AFAIK.)

Due to the lack of seeing the 5 GHz SSID, we connected to the 2.4 GHz SSID. All went well.

Keeping all variables as constant as possible, we then conducted performance testing.

Things got interesting fast.

With Wi-Fi Multimedia (WMM) turned on in the router, the ping times are about 50% slower with the new router than the ancient one. Overall download speed, however, is about 25% faster.

With WMM turned on, the ping times are about equal to the ancient router, but overall download speed is reduced by about 25%.

Obviously, this is not ideal.

Is this normal? Any tips to get a fast ping time and a fast download speed with this setup... to at least match a 10 year old bottom-end router?

If your using a n type WiFi max speed is 300 met but AC is 3 gig so that's part of the problems it won't support
5 g network. It's also a problem in the two speeds aren't compatible you best bet is to get an AC adapter which are dirt cheap now so you can use 5 g and get max speed at the moment your driving a racing car in a ploughed field