[2021] EVE Client is reducing my internet bandwidth to zero

It’s possible the router is closing half open connection or not allowing half open connections. I would recommend you try updating the routers firmware and see if that resolves the issue.

I found some guides here on this page. Please note this is a third party website that is not associated with CCP. You use the information pertained there at your own risk.

Internet Disconnects When Playing Games: 6 Fixes - Internet Access Guide.