The maximum segment size thing worked thanks!
Couldn't install Killer Network Manager, I need the hardware to go with it. But yeah that worked fine thanks.

What are the specs of the dedicated server, such as CPU and RAM?

CPU: 2 x 2.4Ghz Six-Core E5-2440
RAM: 32GB

Killer Network Manager to prioritize the Factorio traffic
I also experimented with the server settings JSON by modifying the 'maximum segment size'

I use CAT-7 cables for my setup but ...

Ah, sorry. I figured they meant an ethernet switch which I wasn't using.

I tried a different router but the same thing occurred. I'm not sure what else it could be.

Sorry, where was a different router suggested?

But it still confuses me why the internet may be involved at all. Maybe for my friend but why would it lag for me when connecting to the server locally?

Anyone have thoughts on this?

I don't have a switch though, the server and PC are plugged into the internet modem.

I connect to the server via its local IP address.

I'm not sure why the server might be causing an issue, as it has good specifications too.
What else can be tested?

Sorry, Linux is not my strong suit.

How would I go about fixing this? I'm not sure what switch you refer to.
I bought this server specifically for hosting the game 24/7, keeping my PC running constantly is out of the question.

Huh sorry.

Log File:
https://drive.google.com/file/d/1L95WO7 ... sp=sharing

Screenshots:
https://imgur.com/U3FD5j4
https://imgur.com/iJTKGla
https://imgur.com/PE0iisM

Hello, I'm trying to host a game and no matter what I do both me and my friends get huge lag spikes and rubber banding.
Sometimes the latency will be 7-10ms and sometimes it'll jump to 150-200ms and jump around everywhere. I've tried looking on other posts but I simply don't know what to do ...