Router set up as access point giving unstable connection speeds

[graysenandrew18]

I have a gigabit connection at my house over fiber optic, but the isp only installed one ethernet port in the house, which goes to my main router (Netgear R6700v2). Where my room is, there is poor wifi reception, so I ran an ethernet cable from the lan port of my main router to the lan port of my secondary router (ASUS RT-N65R). I have the ASUS setup in AP mode in the settings menu:

On my computer which is plugged into the lan port of the ASUS, I get almost full gigabit speeds consistently:

However, when I connected my phone to the ASUS, even while right next to the router the connection is very unstable and varies wildly:

Any ideas as to what is causing this?


EDIT: I ran some more tests and the speed is all over the place:

 

[Petrossa]

Right next to the router is not necessarily the best place to be testing from.
Having said that, perhaps you are picking up interference from an outside source. Have you tried changing Wi-Fi channels to something less crowded?

 

[graysenandrew18]

Right next to the router is not necessarily the best place to be testing from.
Having said that, perhaps you are picking up interference from an outside source. Have you tried changing Wi-Fi channels to something less crowded?

I scanned for interference and I saw an unlableled signal on the next channel over that would constantly spike and then dissapear:

So I moved it to another channel, and it seemed to follow the network even after a change:

I can't imagine why it would stay linked like that unless it was the router itsself creating the interference. Here are the wireless settings:

 

[graysenandrew18]

The problem turned out to be the chromecast audio I had connected to the wifi network. During the setup process the chromecast creates its own network for you to connect to. Even after setup, it would put out a stronger signal than the router on the same channel when I was close to it. The problem was resolved by factory resetting the chromecast device.

 

[Petrossa]

Ah, nicely done!