Solved! Can’t get my cox universal remote to work on my rca ultra 4k tv

Solution
"Universal" remotes aren't. There is only so much capacity for IR codes in the remote. If the codes aren't there you can't add them. A newer remote might have the codes you need. Even though you access the preprogrammed codes with a 3 or 4 digit number that isn't the IR codes but the location they are stored in so find the number for another make and model remote is useless.
The Logitech Harmony remotes are programmed from their huge online database so they almost always have the codes. If they don't you are instructed to teach them into their database so the next user will find them.
"Universal" remotes aren't. There is only so much capacity for IR codes in the remote. If the codes aren't there you can't add them. A newer remote might have the codes you need. Even though you access the preprogrammed codes with a 3 or 4 digit number that isn't the IR codes but the location they are stored in so find the number for another make and model remote is useless.
The Logitech Harmony remotes are programmed from their huge online database so they almost always have the codes. If they don't you are instructed to teach them into their database so the next user will find them.
 
Solution