THR 22-100 will not connect to the mother ship

If everything is actually still working, then you're probably OK. Are you still getting Guide Data updates?  And you can schedule recordings, right?

Everything works except PPV, that's likely due to the fact we only get SD.

Some PPV titles are available on SD format. Try this quick fix here DIRECTV Error Codes 731, 732, 733, or 736 | DIRECTV Customer Service & Support for PPV issue. Let us know if this helps. Veilka, DIRECTV Community Specialist

The THR22-100, as far as I'm concerned, hasn't gotten a software update since 2012 or 2013 and doesn't support DIRECTV on Demand anymore.

While it does still work for HD and DVR, it doesn't support Whole Home DVR.

Also, scheduling recordings is done through the satellite 101, not through the Internet. So, this isn't using your internet connection. 

The THR22 is no longer connected to DVR services even though it is physically connected to the internet so you can't pay for PPV with the remote and On Demand is gone also. Scheduling recording from your DTV account is done using the sats. No idea if DVR services is on TiVo or DTV side. The OP has posted this before. The THR22 is a modified HR22 to run the TiVo software and it is an HD MPEG4 receiver so having SD is not the problem.  You have to pay for PPV  using an alternate way.  My THR22 is doing the same thing and it tells me it is failing to connect to DVR services.

Thanks

 We really like the TIVO interface, having a THR22 for DTV, and a Romeo OTA for locals (we get more locals this way than what DTV offered).

 When our THR22 finally dies, we'll likely switch to some cable offering. 

We still have the 18" round dish w/dual LNB. I've been told in order to upgrade we would need the large dish, mounted on the roof, and remove neighboring trees. These are non starters hence the move to cable.

I also had a Romeo OTA 4 tuner switched to an 4 tuner Edge that weakneess.com upgraded to 2TB but it appears TiVo is no longer making 4 tuner models.