A fresh install of fedora 31 with zawertun copr repos for plasma 5.17.4 has very limited ethernet speed.... until you discover, that in systemsettings / connections / ethernet / wired the default speed is set to 100 MBit/sec In my opinion, this should be set to 'allow auto negotiation' by default, especially if you have gigabit ethernet and your system does not make use of it
It's a default connection created by NetworkManager, we do not automatically create connections, not even when there is none.
Bulk transfer as requested in T17796