This is my first post so go easy on me.
I recently started noticing my server becoming slow so I ran a internet speed test and it turns out my speed is around 10Mbit/s no matter what I do. My internet speed is 350/50 Mbit/s and I can easily get around 270 even on WIFI (the server uses ethernet). This effects everything from downloading updates, torrents to streaming on Plex as well as transferring files to the server. I ran the speed test with iperf and inside the browser on Unraid. Let me know if there is any more info I can provide as I have no idea how to proceed. Thanks for your help. 

klay-diagnostics-20221215-2303.zip

From ethtool.txt

 

Quote

Settings for eth0:
    Supported ports: [ TP     MII ]
    Supported link modes:   10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Supported pause frame use: Symmetric Receive-only
    Supports auto-negotiation: Yes
    Supported FEC modes: Not reported
    Advertised link modes:  10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
                            1000baseT/Full
    Advertised pause frame use: Symmetric Receive-only
    Advertised auto-negotiation: Yes
    Advertised FEC modes: Not reported
    Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                         100baseT/Half 100baseT/Full
                                         1000baseT/Full
    Link partner advertised pause frame use: Symmetric
    Link partner advertised auto-negotiation: Yes
    Link partner advertised FEC modes: Not reported
    Speed: 10Mb/s
    Duplex: Full
    Auto-negotiation: on
    master-slave cfg: preferred slave
    master-slave status: slave
    Port: Twisted Pair
    PHYAD: 0
    Transceiver: external
    MDI-X: Unknown
    Supports Wake-on: pumbg
    Wake-on: d
    Link detected: yes

This indicates that your NIC can only negotiate a 10Mb/s connection between itself and the switch to which it is connected.

 

I would start by making sure the CAT-5 cable is firmly seated on both ends.

 

Next step would be to try a new cable. 

 

Then reboot the switch.  

Then switch to another port. (These two could be done in either order)

 

Make sure that the MTU on the switch is set to 1500.

I can't believe I didn't even consider checking how the cable was seated, I'm an idiot. Thanks!