Hello all

I'm writing this post because I have no other ideas what to do. 

In my house I have a Archer C6 v2.0 router and recently I've switched to gigabit internet connection. When I've switched to this my router couldn't reached gigabit speeds on lan cable so I did a factory reset.

After the factory reset it, I've done the router configuration, used the same name for 2.5ghz and 5ghz along with Smart Connect turned on, and on cable I could reach gigabit speeds however the WIFI speeds are dropping for laptop devices while for mobiles there are no issues, when the 5ghz wifi is on.

I did a speed test on 2 laptops both connected to 5ghz and it starts good reaching 300mbps and suddenly drops to 1 - 2 mbps (even lower). At first I though that is my laptop and tried with a different laptop and same behavior. After that I've switched to 2.5 ghz wifi and got the same behavior.

I've also have a repeater configured as access point and is connected via lan cable (RE315) and on that the WIFI is working decent. 

What I've noticed that is the 5ghz wifi that is causing all these problems but I don't know why because both laptops network cards are 5ghz compatible and on mobile devices everything is ok. 

So what I've tried is to see if the issues will go away:

- Turned off smart connect 

- Set different name for 5 ghz

- Flushed DNS on laptops

- Router restart

- Installed a wifi analyzer to check if there are channel overlaps and configured the recommended channel by the application

The only way is to keep 5ghz turned off and have speeds of: 79.66 mbps for download / 137.24 for upload.