DonkeyOfWallStreet

One continuous file or multiple smaller files?

One large file should transfer a lot faster.

You got answered on r/mikrotik ?

Ok it sounds bizarre that it all worked but the weird results over the powerline when you added the router.

Does the quest work with the pc without internet? Just the 6g router.

The 6g is a full router it's not an Access point that has ethernet ports?

If you plug the power line direct into your pc do you have internet?

You need to separate things here a bit.

I'm confused when you're mixing ssid and physical wired ethernet.

Is the pc wireless? Or wired? If wired with powerline do you disable WiFi?

I got powerline adapters because the WiFi mesh I had was getting crushes(makes sense airwaves are saturated) back haul is now powerline and I don't have to run cables. Was going to put one out in the garage too.

I'd thought the powerline would be lower latency to the router than wireless but wifi6 is really good.

Mailcow.email

Mailinabox

Vyos which edgerouters use

https://docs.vyos.io/en/equuleus/configuration/loadbalancing/index.html

But maybe get something that's not edgerouter

There's mikrotik too

Finally you could look up bonded wan which would give you a 2 Gbps connection...