Gateway specs

I am trying to figure out which gateway or modem / router to buy to replace my Arris TG 1682 that I'm renting from Xfinity.

I'm getting confused where it says 

WiFi (2.4 GHz) Download Speed(i)

WiFi data is not available for this device

WiFi (5 GHz) Download Speedi

• WiFi data is not available for this device

I'm not sure what Wi-Fi data is not available for this device means.. 

A lot of the modem router combos say this. 

**This device is compatible with your service download speed of 75 Mbps.

Device Type

Wireless Gateway

Wired Download Speedi

Up to 948 Mbps

WiFi (2.4 GHz) Download Speed(i)

WiFi data is not available for this device

WiFi (5 GHz) Download Speedi

WiFi data is not available for this device

Voice/Telephone enabled

No

Built-in WiFi

Yes