@Prikleypear
If your 5GHz is showing the correct speed than likely the issue with 2.4GHz is congestion. You will want to check the channel and channel width being used. I would recommend channels 1,6,11 as they have the least ammount of overlap with other channels so should have the least ammount of interference. They are the most used channels so congestion may be a issue. If that is the case try reducing the channel width to 20MHz. this will narrow the band a bit and improve the throughput. Channel settings are always trial and error though. You can use a wifi anyalzer to find the least congetsted channel. Lastly make sure the frimware is up to date.
Best