Try using wifi and connect to a phone hotspot to bypass your router. See if the problem continues.

When you say that it failed, what is happening? Does it reboot?

If so, I'd guess this is a drive problem.

See this place for a link to replacement drive kit options:

https://www.weaknees.com/upgrades.php

No, it gives a C111 error, says it's having trouble connecting, although it did say it's set the time, so not sure what the problem is. I was able to do the network tests where it checks TCP ports and DNS, that worked great!

I tried to connect via my cell phone but it never connects to the wifi hotspot. I found a support article on TiVo.com that says Cell will not work for connecting to TiVo. But since my duplicate TiVo is working GREAT on that EXACT same connection, ethernet plug and everything, it makes me think it's NOT my network.

I'd at least try a router reboot, but I do think you have a bad hard drive.

I had already tried the router reboot. Even ran a cable from the modem directly to the TiVo. I have two other TiVos that are not having connection issues on the same network. So I took your suggestion and popped another HDD in and got the same issue, although the error number is C211 now, even when I put back the original HDD. Perhaps I just got it wrong when I originally posted. I also tried swapping the coin battery, same issue. I have moved the broken TiVo to the dinning room table with it's own TV and the issue remains. Any other things I could try? I saw someone mention routing the traffic to a different server at TiVo...

I don't know of any way to route traffic differently to another server at TiVo.

Connecting via cell hotspot definitely works for testing. It's not a good long-term solution because it's not always-on, but it is a good test. I'd try to pursue that a bit.

Well, I gave up. Looks like the part of the TiVo that does the connecting is also the part that the LifeTime subscription is attached to. Fortunately the Summer Breeze 2019 offer came around so I moved my LifeTime subscription to a Bolt. Didn't know much about them as I have a 720P Plasma so I don't need 4K. When TiVo was offering to sell me a new TiVo to move the subscription to they only offered me an OTA *OR* a Cablecard Bolt. I had no idea they still made one that does both like my failing TiVo Roamio. I ordered the replacment and it arrived and I was able to set it up with my cablecard but it also would have worked with OTA (assuming I ever give up on Xfinity). It also doesn't need my TiVo Stream, and it seems to have better performance than the old setup. Perhaps that's just me imagining that newer is better.

Tried to activiate my soon to be traded-in TiVo one last time, and it still won't connect, but I have three others that will. Strange happenings. I at least got my money's worth out of that TiVo in the two years it worked for me, but just barely. And at least I was able to preserve the Lifetime for just $99 on this new TiVo.

I did order a 3TB drive for it, so I don't get to far into using the new TiVo before I have it upgraded. Thanks for the help on trying to figure this one out...

Thanks for the post - sounds like a pretty good resolution to the problem.