2.4Ghz WiFi is going to give you around 50Mbps (for b and g) and closer to 100Mbps (on 802.11n) theoretical speed with very ideal conditions. Throw in distance, interference and congested channels and you are looking at 50-70Mbps at most.

5Ghz (on the 802.11n) might give you better but still within 100 to 200Mbps depending on distance, as well as your hardware (bonding channels on some routers will allow you to hit up to 600Mbps in theory). Keep in mind the 5Ghz band while providing higher throughput, drops off significantly as you get further away from the AP compared to the 2.4Ghz band.

If you really want to have >500Mbps stable WiFi, you need to get on the 5Ghz AC band, which allows up to 1.3Gbps on a single channel, and capable of going all the way up to 7Gbps on certain router models. TIME supplied c1200 is not going to give you anything more then 200Mbps even on the AC band (unless maybe if you stand right next to the AP). The issue is a lot of routers are auto configured to switch bettern 2.4Ghz and 5Ghz, and most of the time, you are only connecting on the 2.4Ghz band instead of 5Ghz AC when you walk away from the AP.