Server issue or my router?

[billsey]

I'm having problems connecting from outside our local network to a server running 1.1.9.3. When I sniff the connection with Netmon 3.4 I see:

TCP:Flags=......S., SrcPort=54827, DstPort=15900, PayloadLen=0, Seq=2427985101, Ack=0, Win=8192 ( Negotiating scale factor 0x8 ) = 8192
TCP:Flags=...A..S., SrcPort=15900, DstPort=54827, PayloadLen=0, Seq=2095005250, Ack=2427985102, Win=8192 ( Scale factor not supported ) = 2097152
TCP:Flags=...A...., SrcPort=54827, DstPort=15900, PayloadLen=0, Seq=2427985102, Ack=2095005251, Win=256 (scale factor 0x8) = 65536
TCP:Flags=...A..S., SrcPort=15900, DstPort=54827, PayloadLen=0, Seq=2095005250, Ack=2427985102, Win=8192 ( Scale factor not supported ) = 2097152
TCP:[Dup Ack #329]Flags=...A...., SrcPort=54827, DstPort=15900, PayloadLen=0, Seq=2427985102, Ack=2095005251, Win=256 (scale factor 0x8) = 65536
TCP:Flags=...A..S., SrcPort=15900, DstPort=54827, PayloadLen=0, Seq=2095005250, Ack=2427985102, Win=65535 ( Scale factor not supported ) = 16776960
TCP:[Dup Ack #329]Flags=...A...., SrcPort=54827, DstPort=15900, PayloadLen=0, Seq=2427985102, Ack=2095005251, Win=256 (scale factor 0x8) = 65536
TCP:Flags=.....R.., SrcPort=15900, DstPort=54827, PayloadLen=0, Seq=2095005251, Ack=2427985102, Win=0 (scale factor 0x8) = 0
And the connection is aborted with a "Connection failed - Error reading Protocol Version". It looks to me like the socket doesn't come up because the ends can't negotiate a TCP window scale. Would this be an issue with our router (which hasn't had a firmware upgrade in years, and this all used to work) or with the latest uvnc server? I've tried other (RealVNC) clients with the same result, so it's not at the client side...

[Rudi De Vos]

An application just tell the OS to connect the lower parameters like winow or mtu size
are set or negotiated by the OS.

You also have the same effect when a firewall jump in and break the connection...