I want to share a fix that took me a long time to track down, in hopes it saves others the same frustration.
SYMPTOMS
• Samsung phone screen mirroring to my TV stopped working entirely
• iPad took multiple attempts to detect a wireless printer (AirPrint delays)
• All phone and TV settings appeared correct
• Verizon support was unable to identify the cause
WHAT I TRIED THAT DIDN’T WORK
• Checked and reconfigured all settings on my Samsung phone and TV based on Samsung’s support website
• Contacted Verizon Fios support — they could not identify the cause
• Reviewed my G3100 router settings without finding an obvious culprit
THE CAUSE
I had OpenDNS configured on my G3100 router for family content filtering. What I didn’t realize is that the G3100 has a separate built-in feature called DNS Rebinding Protection that activates alongside custom DNS settings. This feature interferes with mDNS (Multicast DNS), which operates on UDP port 5353 and is the protocol that Samsung Smart View/Miracast and Apple AirPrint both rely on to discover devices on your local network.
THE FIX
1. Logged into my G3100 admin panel at myfiosgateway.com (used the Admin password on the back of my router)
2. Go to Advanced → Security → DNS
3. Disable DNS Rebinding Protection
4. Test screen mirroring and/or printing
IMPORTANT: Disabling DNS Rebinding Protection on the G3100 has NO effect on OpenDNS filtering. OpenDNS operates at the level of external domain lookups and continues to block malicious and inappropriate content for every device on the network. You‘re are not giving up your content filtering by making this change. DNS Rebinding Protection is a separate router-level feature that guards against a different and relatively uncommon attack type.
Hope this helps someone — it was a tough one to track down!
