How do I get Lan Preview working again?

I just got a new router. I set up LAN preview in C2 according to Ashley's guide. Everything worked fine; previewed in all browsers, previewed to my mobile.

Now...it isn't working. I haven't changed anything that I can think of. This is the error I'm getting:

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I am running C2 as an administrator. I've double checked this. I'm using r190 stable. I also tried a separate instal of r192 beta, same thing.

Any ideas where to start here?

If you haven't tried it already, perhaps delete the Firewall Rule you set up to enable LAN preview and create a new one. Perhaps, if the new router didn't throw the settings off, like so much to do with Windows, the old rule somehow became corrupted...

Colludium

Thanks for the idea. Actually, though, I just figured this out 5 mins ago: somehow, my router's ip address had changed slightly. I just went to C2's 'preview on lan address' setting, picked the top suggestion (which had 1 number different), and everything worked.