This has been driving me nuts for months now.
I switched to Comcast back in February for faster internet. They gave me a Cisco DPC3939 gateway and hooked everything up as normal. Everything works as expected... or so I thought.
I like to play a game called Dungeon Fighter Online in my spare time. It's a really good game... when it stays connected. Every so often I get a "disconnected, check your internet connection blah blah blah" message even though my internet stays connected. This game uses peer-to-peer for interactions with other players. Here's the kicker: when I get disconnected from the server I can still see everybody in my party running around and doing things as normal. I don't even lag when it happens. I cannot have disconnected from the internet... something is wrong.
Also I recently decided to try discord and I realized that if the game tells me it disconnects Discord says "No Line" at the same time.
The problem? It happens randomly throughout the day. Sometimes it happens twice in a few minutes, sometimes it doesn't happen at all for the whole day. I could be idling, doing things ingame, doesn't matter. If I check the logs on the gateway I see the following under Firewall Logs every single time I disconnect.
FW.IPv6 FORWARD drop, 1050 Attempts. 2015/10/13 19:19:43 Firewall Blocked
(It's one hour slow due to DST.)
The number of attempts varies, but it's always a drop. I printed out a month's worth of disconnects not too long ago... it was a whole page of the same errors!
And get this, nobody else says they lost internet. I called Comcast about the issue and they even said there hadn't been any disconnects on their end for the past 7 days!
I also see the following:FW.IPv6 INPUT drop, 107 Attempts. 2015/10/13 18:58:08 Firewall Blocked
under firewall logs for every forward drop as well as a few[Docsis]: No Ranging Response received - T3 time-out 2015/10/13 15:48:00 Critical
under Event Logs. The no ranging response received message does not seem to correlate with my disconnects, however.
DFO and Discord are the only programs this happens with that I have found so far. Everything else including Brave Frontier stays online! I have Windows 10 but the disconnects have been happening even before 10 was available. Before I call comcast again I want to figure out whether I can fix this by myself by putting the DPC3939 into bridge mode or something as I suspect this is a gateway issue. I have tried disabling the firewalls and the issue remains. I'm at the edge of my sanity! Help me!