Have you had them try to re-provision it? I’ve seen ISP’s send the wrong provisioning or it not go through. 

Since I tried switching from a different model cable modem, I assume they had to provision it.  I know they had to activate it.  I don't know what they do internally, though.

Did you contact them to see if they can reprovision it? or check its status if its acdtivated?

Yes, they activated it and could see it online (and control it for reboot), but could not see my router nor phone connected 

so the t25 has 2x ethernet ports but the vast majority of ISPs only support 1 connected device. 

So try this. 

Power off the modem and the router. Disconnect everything from both even the coax from the modem. 

Wait at least 2 minutes. 

Connect the coax back to the modem. 

Turn it on and wait 2 minutes. 

Connect port 1 on the modem to the wan port on the router. 

Power the router on and wait 2 minutes. 

Try to run the internet setup on the router. 

I believe we tried a lot of these combinations, spending almost 2 hours to no avail.  Elsewhere on the net I read that it won't work since each cable company has its own firmware.  I didn't ask them to 'push their firmware' since I wasn't aware of this at the time.  I'm dreading spending another 2 hours without first getting all the facts. It's worth renting their modem compared to the hours I've put in, but willing to give it one more shot if they can push their firmware.

Their “Firmware” is part of the provisioning when they provision it.