A couple days ago I set up a MoCA network with a handful of Actiontec MI424-WR (rev F) routers off eBay. Configured using info on AVS forum (apparently I can't post links yet...) - basically - disable wireless, disable broadband coax, disable IP address distribution, assign unique IP.
My setup is CenturyLink Q1000 DSL (bridge mode) -> Netgear WNR100 -> everything else. Comcast for digital TV service. I've got two TiVo Premieres, an HD, and an S3. The HD is direct ethernet; the primary Actiontec + Netgear are at the same location. Premieres and S3 on MoCA. Everything worked great, I could transfer between all of them much better than I ever could on wireless. Went to bed, got up the next morning, and none of them could see each other.
Verified from a computer that I could not log in to the admin screen of the 3 remote Actiontecs. The primary one, connected to the router, I could get to OK. After rebooting/ unplugging/ the remote Actiontecs, everything eventually came back up. Next day, again, all had lost connection.
The wiring in my house is far from optimal, I know there are a couple of splitters buried in walls with no way to get to them. In the interest of trying to minimize loss, I'm using a Holland DPD2 diplexer to split the frequencies at each coax outlet (vhf outlet to tivo, sat to actiontec.) I put a 4way 2-2150MHz splitter at the cable inlet - SWM MSPLIT4R0-03 - with a POE filter on the input side. Frankly I was surprised it all worked. But it did.
I'm not including a number of details here for the sake of brevity. I can certainly provide more if it would help. It just seems like there may be something basic I'm missing in the router settings. The only other obvious thing I can come up with is trying to reduce signal loss - at the HD TiVo outlet, it reports cable strength as 62. The other TiVos are around 85-100. The HD outlet is also where I have the first ActionTec feeding into the rest of the house, so given that that line is weak, could that be problem? Can a weak signal manifest as having connection for awhile, but eventually dropping out?
(edit - checked Coax Connection Stats for MoCA speed on the primary Actiontec - all devices appear to be ~235-240 Mbps.)
I can run some temporary cables to other locations to troubleshoot, maybe test one coax outlet at a time - but given the connection takes hours+ to drop, that will be a long process. If it is just a router setting, I'd rather figure that out first.