@pedpete 

It could be as simple as turning off and on the modem. Some only will 'connect' to the last device attached to it as it 'remembers' the MAC Address of the attached device.

Power off both the modem and router, then turn on the modem and wait for it to fully come up, then power up the router. This should fix it in most cases.

Also, if you have the A20, the wire from the modem must go into the blue socket, same for the C20.

@IrvSp Thanks for reply. 

I don't know where modem is. I presume it is outside somewhere. I live on RV park. Service comes in on a CAT6 cable. That is all I know.

I can plug that cable into back of computer and get internet.

Take out the cable and put into back of new router C20 into Blue hole and nothing.

My TV and computer both see the new router but the router cannot connect to internet as the computer had done.

I simply thought I could plug it into back of router and it would wifi it all over trailer.

I can't use computer as wifi because it lacks the internal hardware.

What to do.

@pedpete 

Well, that probably explains it. However YOU can avoid this by CLONING your PC's MAC Address to the router.

I'm on an A20 as I said, but I'll assume the C20 (if that is what you have) is the same Graphic Interface. On the BASIC PAGE for the INTERNET is the ability to CLONE the router MAC Address to the Router:

Select that option, SAVE the settings, and REBOOT the router. That should make it work!

@IrvSp Thanks for the great reply and steps.

Followed them easily but still no joy. Am now accessing chat tech support.

If they have an answer I will post.

@pedpete Chsat support at TP never found the problem.

Will have to return product.

We spent at least 1.5 hrs.