You've been there before! The only part which might apply to your situation is 2C part 1. It's clutching at straws, but you might try running fix-disk (from the Telnet maintenance-mode menu). Corrupted recording files can cause the delinquent half-awake state, but I suppose they might result in reboots. If all else fails you could try archiving off all your recordings and deleting, see if the problem goes away then bring back half of them, and half of the rest, etc, to subdivide where the problem is.
What worries me is that both of your HDRs do the same thing, and really I would prefer to look for explanations which are common to both - which suggests something else on your network or something about the configuration. I think the first thing to do is to disconnect your Twonky device from the network (temporarily, anyway) and see if the problems go away. Remove the dlna-filter package if necessary.
It's always a good idea to go back to basics: you could, for example, with the Twonky device off the network, strip the HDRs back to standard, set DHCP, and test the native streaming facilities as intended.
Alternatively: give up on DLNA and use network-shares-automount.
