Any progress on this? I just noticed the same thing is happening to my router.
DIR-820L A1, firmware 1.06, Canada
Cable Internet, 50Mbps DL/3.5 up, Motorola SB6120, Dynamic IP
I'm also getting "daemon.err: miniupnpd[23028]: Can't find in which sub network the client is" very often. Disabling UPNP makes it go away, but then I loose functionality.
Apr 1 19:57:40 daemon.err: miniupnpd[23028]: Can't find in which sub network the client is
Apr 1 19:57:38 daemon.err: miniupnpd[23028]: Can't find in which sub network the client is
Apr 1 19:57:36 user.warn: kernel: add 0.0.0.0/0.0.0.0 to access 0.0.0.0/0.0.0.0:33170 directly[10/10].
Apr 1 19:57:36 daemon.err: miniupnpd[23028]: Can't find in which sub network the client is
Apr 1 19:57:34 user.warn: kernel: add 0.0.0.0/0.0.0.0 to access 0.0.0.0/0.0.0.0:0 directly[10/10].
Apr 1 19:57:33 daemon.err: miniupnpd[23028]: Can't find in which sub network the client is
Apr 1 19:56:32 daemon.err: miniupnpd[23028]: Can't find in which sub network the client is
Apr 1 19:56:30 daemon.err: miniupnpd[23028]: Can't find in which sub network the client is
Apr 1 19:56:28 user.warn: kernel: add 0.0.0.0/0.0.0.0 to access 0.0.0.0/0.0.0.0:62780 directly[10/10].
Apr 1 19:56:28 daemon.err: miniupnpd[23028]: Can't find in which sub network the client is