Reading this thread, the OP has had three different issues... I'd start by checking the coax diagnostics by holding right arrow on front panel and press guide for approx. 1 second and release both. This only works for the H24 and HR24 boxes and the Phy level test cannot measure the node loss at its node (N/A will be displayed; if multiple 24s are in the setup, the node loss will be measured by a remote 24). Running Coax Diagnostics, Phy Level s/b LT 60 (measured dB loss directly proportional to coax length); Phy rate mesh s/b GT 215 (this is the measured speed of your MRV/DECA connection) for passing results. You can post these results. If failing, the thing to check for is loose coax connections or missing terminators on unused ports of splitter or splitters. The green-labelled directv splitters s/b used since they're designed to pass the DECA frequencies without insertion loss that a standard splitter will yield.
suggested work-arounds;
MRV device drops of the network:
1) Verify your router is not limiting the max number of Clients; some Linksys routers have multiple settings and default may be set to max of 5 Clients.
2) Use static IPs outside the DHCP range of router; do not use reserved DHCP as static, not a good substitute for Directv, ATM. Static is as simple as menu navigating to Network, select advanced tab and entering a unique IP address that is known to exist outside the DHCP range of router. Net mask: 255.255.255.0 Gateway; router's IP (ex. 192.168.1.1) Alternate DNS server could used as well, try 208.67.222.222 or 208.67.220.220 (OpenDNS). should connect.
TV APPS:
If using static IPs, you can port forward your router to start network services (this may not work but may be a method to narrow the problem)
1) Select ports to manually assign for each Directv box starting at TCP port 27171. It's a good idea to assign odd ports as STB ports and even ports as audio services ports. For ease of memory, assign them sequentially: 27171/27172... 27173/27174... 27175/27176 as so on... Assign these in your router to the static IPs. In addition, add these forwarded ports to each static IP: UDP port 1701 and TCP port 443.
2) Select Network Services tab, select manual and enter the port numbers you assigned to each IP. Run connection test. Run it again if you get message stating, "Network Services has started but Connection Test failed". Twice s/b enough to see the Congrats...running.
Note; these steps may only facilitate connection to TV APPS; there may be an issue where ISP or router blocks connection or the server is not recognizing a valid Receiver ID (these are unknowns). The connection test results w/b important to pass along to Directv if all appears well but still getting errors for TV APPS.
MRV SD playback fails
I've seen a few reports with the problem but have not seen it myself; I MRV SD content for my daughter daily w/o fail. I'd try a menu restart if any MRV attempt fails. I have seen MRV Clients fail to stream a recording that starts with the message that all or part of the recording was lost due to a signal error. Resuming past that message locally would help the Client if resume was selected. I think a lot of these MRV issues have been addressed with f/w upgrades but more are still needed.