Sunday, December 16, 2018

PSA: If you use Sophos UTM (and possibly Sophos XG), do not enable UDP flood protection as it will kill Google sites

I have been trying to figure out for a while why my speeds to any Google site, such as youtube.com, photos.google.com, images.google.com, etc were limited to 2 Mbps. I could not stream videos at more than 720p and it would take a very long time to upload and download backed up photos from Google Photos with my Pixel 2 and 3. Long story short, the problem was I had was that UDP Flood Protection was enabled on my Sophos UTM router under Network Protection > Intrusion Prevention > Anti-DoS/Flooding. Apparently, Google uses a new network protocol called QUIC for their sites that uses the UDP protocol to establish a boatload of simultaneous connections. Sophos routers see this as a UDP flood and starts rate limiting the connection. Apparently, you can create an exception for UDP traffic on port 443 to get around the issue, but I just said F it and disabled the UDP flood prevention feature. Hopefully this helps somebody else out.

https://en.wikipedia.org/wiki/QUIC



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