Following sequoia update I cannot use cabled ethernet. Only wifi

Let's try a simple test.

With your Mac connected to your local network by Ethernet:

1. Open a Terminal session, and then, enter: dig www.apple.com. In the result, look for the value for status. Success would be status = NOERROR
2. With the Terminal still open, enter the following command: dig 1.1.1.1 This time success would be: status = NXDOMAIN

If the first step fails, but the second does not, then you have a DNS configuration issue on your local network.

Any add-on security apps, add-on anti-malware apps, add-on firewall apps, or add-on VPN apps? If so, remove all, restart, and try again.

Check your Wi-Fi router for any available firmware updates, and apply the latest. Then restart your Wi-Fi router, and test again.

I disabled and removed adblock.

I doubt Adblock would do that. Isn't it a Safari Extension.

You need to find something that purported to give you internet security (like a VPN) or other useless maintenance that you installed and provided your admin password to install.

I have the impression Apple is trying to unify connectivity to iPhone, tablet and laptop.

Or, you have some third-party software blocking access to Ethernet. Or, its just misconfigured somehow.

If you have your ethernet set on manually set it to automatically. I read on a discussion yesterday that it worked for the person after he had a chat with Apple Support.