Whole Home Equipment Upgrade - Do or Don't

First off it is a scam, DTV never calls to upgrade your equipment.

Second reason it is a scam, upgrades always come with a 2 year commitment.

You can try running a search for          clearmybox     that will dump the guide data and other things, it will take a day or 2 to rebuild, any recordings set to record will, on each receiver.

I see no reason to upgrade, but if you do want to, all DTV has to run that may TVs is the HS17 Genie2 that is a client only system so you will lose all the HRs and get 7 mini clients all can be 4K if all TVs are 4K at the time of install but only 2 at a time can stream 4K.

Only the 4K clients C61K or the C71WK can output 4K, yes all minis clients can watch recorded programs or live channels provided there are tuners available for each, recording channels uses a tuner so the HS17 has 7 tuners so if you are recording 3 channels at the same time you can only watch live TV on 4 clients.

The Genie-2 (HS17) only allows Clients. That means every TV would be replaced by a Client. That would be a HUGE downgrade from what you have. You would lose all existing recordings, reduce to 7 tuners and 2TB recording space for all TVs to share, and make all TVs dependent on a single box to rule them all (instead of dedicated reliability and independent settings as you have now).

AFAIK DTV no longer has any HR24s in stock.  Some online DTV retailers have them at the full upfront lease fee but not sure if DTV will activate them.

Unfortunately HR24s have been hard to come buy. Some have managed to get them as warranty replacements, but that likelihood has dwindled and supposedly is not available for upgrades (though I have HDDVR still as an option to order when I log into my account).

Authorized Retailers (such as Solid Signal) have kept them in stock. But they are at the one-time lease cost of $199 as a free upgrade or warranty replacement ($19.95 delivery) can only be done through DirecTV. And they still come with a 24 month agreement. As HR20 thru HR24 are like-for-like, I would not pay for that "upgrade" except as a last resort.

As you may know, HR22 is when they increased to the 500GB internal drive for the regular HDDVRs. And up to the 3rd generation Genie HR54 (not revised HR54R1), and even the very first run of Genie-2 (HS17), they supported an external hard drive if the internal was not going to cut it for you (hard cap 2TB for HR24 and below where the Genies had no official max. Either way they only support eSATA).

Per standard policy, no, although there is some evidence Directv has been replacing faulty HR24s recently for some people. With the HR54, you are limited to two 4k streams anyway so another C71KW would be a good replacement for the Hr21 if you call Directv to replace that one, tell them it's faulty (won't power up maybe).

If you tell Directv one of your HR22s is faulty you MIGHT get an HR24 to replace it but there is no guarantee.

The other obvious path is replace everything, with the HS17 replacing the HR54 and all of the HR21/22/24 boxes with clients (including at least one more C71KW). That's what Directv would probably try to get you to do, because that's the current :"standard " solution. But as Juniper says, that would be a real downgrade so none of us would recommend it. 

If it were me I would get Directv to replace an HR21 with a C71KW and leave it at that

The HR54 is limited to ONE 4K Stream. The HS17 is limited to TWO. But you can have multiple 4K Clients, just only one using a 4K channel at a time.

Only replace the HR21 with a 4K Mini Genie or Gemini if you don't need the dedicated HDDVR for the tuners and recording space.

The HR54 can only stream to one 4K mini at a time, only the HS17 streams to 2.

OK so lets have another look at this. 

There's nothing that would cause multiple HR series boxes to all become slow. They don't share anything that could affect them all, except they all use the same software. If you go to the server/client model, then of course the software will change but there's no guarantee it will be faster. One thing juniper mentions which can be a deal-killer with the client server model is that because all the clients share the same playlist you can't separate the recordings, everyone has access to all the recordings so each user can delete anything. For me this would be a deal-killer, 

In any case I  doubt that Directv would be willing to replace all your equipment free of charge.

What would I do? Stick with your current configuration. If one of the HR  boxes is notably slower than the others, replace it with a C61K That will give you two locations where you can access 4K. Only one 4K stream can be active at any time, although the "other" C61K will behave just like a non-4K client.

As a "chance" you could try calling and informing the HR21 is dead to get a warranty replacement ($19.95 delivery). If this is successful than you get an HR24 as that is only non-Genie HDDVR to still have in stock.

Check order confirmation. If says 24 month service agreement, then you cancel the order as that was an upgrade. If says anything other than HDDVR (Mini Genie, Gemini, Client, etc.) cancel order. And naturally if they want to schedule a tech than it is a wrong order to begin with.

When you call and get the voice system you can say "cancel" as sometimes the retention agents are more experienced or have slightly more flexible option. Your setup is beyond the capability of a Genie/Client-only setup, so a dedicated HDDVR replacement is the right way to go if it can be ordered.

This is one of the reasons I greatly disliked how AT&T was trying to change DirecTV from customer friendly option. That and instructing everyone that Android users were "GAME OVER" compared to iPHONE users.