PC with Dual Boot, on the network only with Windows

[DarkCorner]

I have a PC with Win 10 Pro and it works correctly: it goes to the Internet, accesses Win Update, downloads programs, etc.
I didn't have to configure anything, neither on the PC nor on OPNsense.

On this PC I created a partition with Debian 12 for Dual Boot, but already at the time of installation it doesn't recognize DHCP4.
If I configure the network manually, then I don't access the APT repositories and therefore I can't install other programs.
Then, from Debian console the ping on the firewall doesn't work either.

On DHCP4 / Lease I see the active PC (green icon9)
I can't understand what it could depend on.

[bartjsmit]

Install a different NIC - yours does not work with Linux

[DarkCorner]

Install a different NIC - yours does not work with Linux

But in DHCP4 Lease there is a green icon, so the NIC has been detected.

[cookiemonster]

I don't have Debian but have Ubuntu I can look at. I imagine the utilities are the same.
What you get from $ip a

[DarkCorner]

Even adding a second NIC, I do not access the Internet.
On the other hand, if I connect the NIC on the Motherboard directly to the router everything works correctly.
So it is the firewall that blocks the Debian partition, while the Windows 10 partition connects without problems.

[meyergru]

Install a different NIC - yours does not work with Linux

But in DHCP4 Lease there is a green icon, so the NIC has been detected.

Nope. You are probably misinterpreting this. If it is the same PC and the same NIC, it will expose the same MAC to the network. So: 1. the old DHCP lease will still apply until it expires (after a few hours) and 2. if it is green, then there is still an ARP entry, which can also still be the one from the last Windows boot that has not yet timed out.

Also, I would look for what exactly does not work:

1. Use "ip a" from the CLI of the Linux host to see if the NIC is detected and picks up an IP
2. Use "nslookup www.google.com" to see if DNS is working.
3. Use "traceroute 8.8.8.8" to verify your routing works and your firewall does not block anything.

The second part is essential because I often see that Debian and Ubuntu do not get the DNS resolver via DHCP.

Also, keep in mind that the firewall has absolutely zero indication about your PC using Windows or Linux, so why would it block one and allow the other? Before you say that the firewall blocks your Linux PC, look into the firewall logs to verify that.

[BillyTheKid]

I had the same problem...
The solution was to set the VLAN to U (= untagged) on the switch port on which the PC-NIC is connected.

Best regards

[headbanger]

This could be a DNS issue. Are you using the DNS provided by the DHCP request or are you manually entering the DNS server?  Windows, for example supports DOH, Linux does not unless you install DNSCRYPT.  If you have no rule to allow port 53 and you setup DOH on windows then windows would work fine but linux would fail.  Check your logs, is port 53 blocked or is it blocked on the server used by linux?