Ethernet is completely down

I had an XV gateway from 2020. Wi-Fi was working fine, but wired ethernet was intermittently slow. I called Comcast and a technician came out and stated that the cable coming in from the street was damaged and wet. He replaced the entire cable coming into the house. He also removed a splitter. that he said was no longer necessary. I’m assuming that this is because we no longer have separate cable and ethernet.

Unfortunately, this did not fix the problem. As a matter fact, the ethernet got a lot worse. Wi-Fi stayed OK. Called Comcast and a second technician came out and replaced the gateway. Unfortunately, after this, the ethernet was completely down.

Then I realized that when the house was built in 2009 and old switch was used which Could not handle gigabit speeds. So I replaced the switch. This brought everything down, wireless and all.

After several hours and several restarts, the wireless finally came back on, but the ethernet continues to be completely down.

I have scoured this forum for solutions, and I know I am not alone.

Suggestions?