The pins in the other port are probably damaged if it only works on one. You could also check if there’s anything in the port. Another thing to check is using a different cable.

You said this is less than 30 days old? Go to the Apple Store and tell them it appeared after a bit of use. No damage. Try to get the warranty to apply.

I know many people on here will hate this comment, but a 6e mesh router system may work.