Host never recieves SynAck

[CiscoPurpleBelt]

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So capture on host side shows Syn got out to server on my side. Capture on my ASA shows server receive the SYN and keeps retransmitting with a SYN/ACK until connection is reset. At least SYN packet makes it to our server so I suspect possible a route issue somewhere between us to send the SYN/ACK or traffic back? Perhaps load balancer causing issue? Thoughts? Pinging or traceroute not possible due to restrictions. 

[Georg Pauwen]

Hello,

who (what device, what OS) is the host ?

[CiscoPurpleBelt]

I don't know, it is possible a Windows 10 thin client. Shouldn't it at least receive it if the network path if good?

[Georg Pauwen]

What is your server running ? I have been looking around, turning off and/or TCP window scaling and TCP timestamps on your server could be a solution...

[paul driver]

Hello

What service(s) is that host running, can you try to establish a connection on it application service port?
telnet x.x.x.x <port>

[CiscoPurpleBelt]

I don't know. Telnet or SSH is not going to be allowed out through the WAN. If the network path if good, shouldn't the SYN/ACK traffic make it to the host? Just trying to understand what you are thinking?

[paul driver]

Hello

Telnet on its default port maybe denied but you can use it to open up a different port -ie  the application port you have running on that host I assume you must be able to test what you want to access?

Is the fw allowing the service ports you want to access that host with?

Also turn off any software firewall that win10k host maybe be running and test again. 

[CiscoPurpleBelt]

I can see, not sure if user with host is able to do that.  If the network path if good, shouldn't the SYN/ACK traffic make it to the host?