This is a common problem, in most cases a second reboot should fix it.
I am not sure what causes this however, it sometimes occurs after EHCP force updates and also Ubuntu updates.
If this does not fix it, try turning it off completely, waiting 5 minute and then booting it up again.
Another thing is to turn of your router, wait 5 minutes and then turn the router back on.
As a final resort, you could try running my EHCP force update script from THIS POST, as the updater has a few fix routines built in. I had to do this once to fix a service unavailable error.
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