Just more observations of problems. :(
I've been digging through the router's system logs and it seems like most of what's in there is inaccurate. For example 80% of the log entries are for Dec 2014! Excuse me but that's still 11 months in the future. Those incorrect log entries seem to persist between reboots too. The only usable log entries start at the last reboot and contain nothing that would indicate what the problem is. Presumably the problem would be in the last entry of the log before it rebooted.
I do see errors in the security log as the DNS server tries to resolve the IP address of a PC that's no longer on my network. Its happening quite frequently but I don't think its related to the problem at hand. Most likely some device had a drive mapped, or DLNA info stored for that old PC which is now in the scrap pile of antiquated equipment known as my attic. :)
Anyone else here using the undocumented setting to get DLNA to work on this router? I remember setting it maybe a year ago. I'm wondering if this has anything to do with the problem. FWIW that URL is
http://192.168.1.1/index.cgi?active_page=6059