R6700v3 slow ethernet, slow wifi

I have poor internet speeds, download speed to be specific, while connected to my router. I have tried connecting directly to my modem (CM500V) and have my usual ~180 Mbps down, but with the router I have anywhere between 5-1 Mbps down. 

 

I have tried the following:

• Resetting my router, i.e. pushing the button on the back, unplugging all of the wires from the device
• Factory resetting it
• Changing the ethernet cable
• Unplugging the modem
• Reverting to an old firmware version R6700v3-V1.0.2.66_10.0.48 
• Upgrading back to the current firmware R6700v3-V1.0.3.66_10.0.50
• Changing the MTU size to 1300, and 1400 from the original 1500
• Switching the ethernet port I use to connect to my pc