How do you resolve the Intel(R) I225 (3) network adapter internet connection issue?

Okay, I got confused and thought you were trying to use the WiFi. But that works and you want to use ethernet?

First off, disconnect the WiFi, possibly disabling that in the device manager. You can turn it back on later but to test that the ethernet is properly working you want it disconnected so it doesn't get in the way.

Next, as long as you're in Device Manager, make sure the drivers for the network card (not the WiFi one obviously) are installed properly, that's a separate device than the one that controls the RJ45 port.

Next check that the cable is plugged into the ports at both ends and that the connection and activity lights are both lit in the back (if both exist, sometimes it's just one.) I like to recheck just to be sure for my own sanity (especially since some of the tabs broke off on mine and I'm too cheap to get new cables.)

Then go into your network settings like I said before.

If there's a firewall that's set to block traffic that could also be an issue, though I'm not sure why it would affect just the RJ45 port's traffic and not the WiFi, but it's good to cover all the bases.

If you really want to get into the weeds I found a guide here https://www.comptia.org/content/guides/a-guide-to-network-troubleshooting

That website is run by the guys who do the certification testing for N+ (among others.) So they know what they're talking about.

If you STILL have trouble after all that, I'd call a friend's gamer kid over, they should be able to figure it out. Best part is you can pay them in snacks or something. 😄