I have noticed that during said speedtest, Deco's CPU utilization maxes out at 100%. Does that mean the unit is just incapable of delivering anything beyond 3.5Gbps?

  @Max_M 

internet Who spf+ are you using 10getenk  depending the switch your using  that might be the issue  yes i love have 10 gb 

  @David-TP Hi, and thanks for the response. 

The SFP+ modules I'm using are optical, not copper. Specifically, they are https://www.fs.com/products/74681.html and matching https://www.fs.com/products/74682.html on the other end, with a generic configuration.

I'm pretty sure they are not in play here though. To isolate the issue, this morning I connected my [Main] Deco to the same router using a regular copper Cat7 cable, and got exactly the same result.

Additionally, I tried disconnecting my second Deco, and testing the remaining one with both (copper and SPF+) conection options, getting the same results.

The last thing to try that came to my mind is swapping the primary Deco role to the other unit – again, exactly the same result.

In all cases, I can confirm on Mikrotik side that the link has succcessfully auto-negotiated as 10G full duplex one.

Very interesting topic,

i am also looking to update my home network to 5gbit download\upload internet next month.

with sfp+ connection with Deco BE95

if you find way to bypass 3.5gbit limit please write your recommendations

I got internet upgrade and after disabling QOS option in mobile app settings i easily got 4.5gbit in both ways download and upload

Router CPU load in this time about 10-15% 

With QOS turned on it was about 2 - 2.5 gbps