@Viision96 If your FW version is an EU, here's the list of FW releases. Have you tried the beta FW from this thread ? (it's in the Recommend Solution post by Kevin_Z) You can revert from beta to the...

:) Glad I could help

Put it to Auto, reboot the device and test again. Any change in your network in the recent two weeks ? What's the device on the cable's other end ? If the device still negotiates 100 Mbps, re-plug...

@Shiv741 That's the culprit : Check this setting: If it looks like in my screenshot then make it: Then observe your screenshot value for Internet port negotiation speed - it should be 1000 Mbps. If...

@AndreMostert Have you tried to hard reset (Method 1) the device and re-configure from scratch to see if that will resolve the peroblem ?

This is a service-provider device, and its FW is not publicly available. You only have QoS for traffic prioritising.