If anyone can shine some light on the current router stats still, I'd appreciate it. It'll be interesting to see if its still reporting send errors on my super router wireless stats page.
It is interesting that the wireless stats show a problem with "send errors", but like a lot of statistics, it doesn't help you understand *why*.
I guess it is likely that the error counter comes from the WiFi chipset, and reports the packets that never got sent out over the air because they never got approval through the CSMA mechanism. If that happens, it suggests something else is transmitting in a way that doesn't let your packets out, or delays them significantly. That "something" may well be a rogue wifi box that isn't obeying the rules. Or perhaps it is something that isn't wifi, and is just stomping across the spectrum.
Had you tried changing channels?
As the problem seemed to extend to a wired LAN connection, but still didn't affect the WAN (I think **), suggests that your LAN is getting overloaded. Perhaps you needed to be running some simple, long-lived, ping tests within the LAN.
I once encountered a problem where the LAN was being hogged ... by a network-attached printer.
** BTW: Your links to your BQM's are all ones to the live graph. As I come to this thread a few days later, I'm not able to see what the graphs showed a few days ago, so can't comment on them. It is usually better to post a link to the graph for the specific day, rather than the live graph, so they remain visible later...