Multiple browsers different download speeds on single thread/process.

I have 4 browsers currently installed on my x64 win 10 pro machine. Two of them download half speed compared to my sync.

Firefox and Chrome when downloading download at 30mbps when using their native download manager, if I use an add-on manager like "down them all" I can download at the full speed of 62mbps.

Then we come to Cent (Chrome Clone) and Edge. These download with the built-in manager at full 62mbps speed. Tested on several downloads and single/multiple thread speedtests.

What gives and how to fix firefox and chrome?

This has to be a windows problem as I have just updated Cent to the 64 bit version and now that is struggling with single thread downloads. What the heck?

So just restored Windows from a backup and now back to Cent 32 bit with no download problems, what the heck goes on.

Fixed it by going to settings network and reseting network, then a reboot and all is well. Took ages to find that button even tried TCPOptimizer 4. All browsers working correctly.