Cannot enable the internet connection when installing Linux on HP Compaq 6200 Pro SFF desktop

I am trying to install Ubuntu 22.04 on a HP Compaq 6200 Pro SFF. I am new to Linux. I realized I cannot enable the internet connection during the install. I installed the OS without the internet but cannot update anything afterwards.
In the Setup, the Storage/Boot Order is disabled in the menu, by default.
The only option enabled there is Storage Options/Sata Emulation that is set to “AHCI Mode“, the other choice (not selected by default) being “IDE Mode“.
“Security”/”Network boot” is also disabled by default.
“AMT Configuration” is always enabled by default and if I disable it and save the setup on exit, it comes back on to “enabled” at the next boot. I have a strange feeling that this AMT is the culprit for not having an internet connection.
I have to say that I had Windows 7 on this PC before and installed Ubuntu without keeping any Windows partition, so wiping everything out.
Could you please point me in the right direction to enable the internet connection during the Linux install? Many thanks in advance for your help. Much appreciated.