To note the issue only occurs when both Decos are powered on.

If 1 of the Decos is off the other runs full speed. I tried this multiple times and it didnt matter which was off the other would be normal speed again.

  @David-TP 

It is reproducable 100% of the time. Due to the location of the 2nd deco I can't directly connect them with a single cable. It goes router > switch and then to deco 1. That 1st switch is then connected to another identical 2nd qnap switch and then deco 2.

The router is a 10GB router provided by Google Fiber and it's model is GFRG300.

Thanks

  @David-TP 

The signal source is ethernet.

Here is a speedtest result as well.

www.speedtest.net/result/a/8824098968.png

  @David-TP 

Here is a test from the 2nd deco.

https://www.speedtest.net/my-result/a/8824870283

Before when it was in router mode both would have similar results to the above. 

Here is a result with the other deco when I don't use wired backhaul.

https://www.speedtest.net/my-result/a/8824881883

As you can see it's faster than Ethernet on the download and only the upload suffers.

Here is my speed test results wired:

https://www.speedtest.net/my-result/d/ce20e4fa-2bef-432d-aa94-de36c08e585b

  @David-TP 

Hi,

I checked but I don't see any email yet.

Thanks

  @David-TP 

After an initial email I have not heard anything back about the issue.