Welcome to the Community!
LAN ports are configured as plug and play. Have you tried to use a different Ethernet cable? How many devices have you tried to connect to it? Was it working fine before?
Can I use wifi and LAN at the same time? - Yes, you can use both connections at the same time.
Please send me a PM with your TPG username or customer ID number to assist you further.
I've responded to your PM and currently waiting for your response.
Were you able to use the LAN connection with your notebook before you transfer to NBN service?
If yes, could you please connect the notebook via LAN and provide me a screenshot of the status of your notebook's Ethernet network?
I would like to analyze this further.