The LucyRTL8125Ethernet.kext has a small bug in it stopping the Realtek 2.5gb ethernet port from connecting when it’s set to Automatic.
If your at the install stage and your getting a warning that you have no internet connection then you need to do 1 of 2 things to correct it.
Install Notes
Method 1
This will manually setup the connection speed of the port and get it working.
Method 2
In Big Sur you need togo into System Preferences -> Network and select the Realtek Ethernet Port (Not the one marked Ethernet 2) and then click on Advanced -> Hardware and set Configure to Manually and set the Speed to 1000baseT then click OK. This will kick the Realtek Ethernet Port into life and keep it that way.
If your at the install stage and your getting a warning that you have no internet connection then you need to do 1 of 2 things to correct it.
Install Notes
Method 1
- Open Terminal and enter the following.
ifconfig en0 media 1000baseT mediaopt full-duplex
This will manually setup the connection speed of the port and get it working.
Method 2
In Big Sur you need togo into System Preferences -> Network and select the Realtek Ethernet Port (Not the one marked Ethernet 2) and then click on Advanced -> Hardware and set Configure to Manually and set the Speed to 1000baseT then click OK. This will kick the Realtek Ethernet Port into life and keep it that way.