E1200 Wireless Client List will not display and causes web UI to temporarily stop responding

Question

I picked up an E1200 and set it up successfully.  I am using wireless MAC filtering, and decided to pull up the list of connected wireless clients (Wireless >> Wireless MAC Filter >> push "Wireless Client List" button).
When I do so, it immediately throws this back:
Immediately after this the Web UI of the E1200 becomes inaccessible.  It still routes traffic, and the router remains pingable, but it will not allow access to the Web UI for several minutes.  The error that appears upon attempt to access the Web UI during this time window is similar to the above, but reads "Error 102 (net::ERR_CONNECTION_REFUSED): The server refused the connection."
I have tried this in Google Chrome, Firefox 4, and MSIE on two separate computers.  Each browser displays the error a bit differently (MSIE, for example, just says it can't display the page and gives no further detail) but the net results are always the same.  I have tried resetting the device to factory defaults in addition to re-downloading the firmware from the Cisco/Linksys website and installing it.  No improvement.
I have also noted that the Log (Administration >> Log; and yes, I have it enabled) doesn't appear to be picking up anything at all.  In fact, the Security log, which supposedly (according to the Help) "displays the login information for the Router’s browser-based utility," is also blank.
Is this a bug, or should I head back to the retailer and swap this device?

Answer 1

Ok - I nailed this down, I think, and it looks like a firmware bug.
Short version is that a factory reset cleared the issue, but during stepwise reconfiguration the problem came back.  Through a bunch of iteration I figured out that if I have the E1200's DHCP server disabled *and* have wireless clients connected to it, the problem I described appears.
Turn the DHCP server back on and the problem goes away.  Turn it off and the problem comes back.  Turn it back on and it goes away.  You get the idea.
If I had to pose a theory here, it's that the initial display of the Wireless Client List, which uses "IP Address" as the default sort, somehow implodes if the E1200 isn't actually assigning those IP addresses to the clients.
When this happens it appears to crash the Web UI wholesale.  Just for grins, while the Web UI was unresponsive, I pinged the router it as before - still pingable - then ran nmap against it - no open ports found on the router.  When the Web UI is functional, though, nmap detects port 80 quite easily.  I have not timed how long it takes for the Web UI to come back up, but it is longer than 5 minutes, and I presume some sort of watchdog process has to detect that it has gone kaput and start it up again.
Final test was to restore my saved configuration from before the factory reset (note that the saved config was done under the same firmware version, and in this config, the DHCP server is disabled).  Boom, problem.  Wait for the Web UI to come back, turn on the DHCP server.  Problem goes away.  Turn the DHCP server off.  Boom, problem comes back.
So, there you go.
Would be interesting if someone could verify this via a test against another E1200.  It may be worth noting that in my baseline test I was also using Manual wireless setup (vs. Wi-Fi Protected Setup), and WPA2.  Didn't make any other setting changes from the factory defaults.  I did not actually have to turn the Wireless MAC Filter on to do the test.  All one needs to do is click Enable on the Wireless MAC Filter tab, and then do *not* click Save Settings - just clicking Enable will light up the Wireless Client List button, which you can then push to get the list.  That is how I handled testing to ensure that neither specific entries, nor the Prevent/Permit setting, nor having the filter enabled in saved configuration were involved in the problem.
Separately, no explanation for the lack of entries in the security log, but that pretty much looks like a firmware bug to me as well.