port numbers reused

[divas80]

Hello,

we have a strange problem with our Cisco ISR4431/K9 router. There is a VM behind it, which is trying to connect a server in Internet.

We have a NAT configuration on the router which allows all other clients to connect to Internet resources without any problem.

Only for this server in Internet we have connectivity issues. In Wireshark capture we see that the request is send to the server from the outer interface of the router, then we see a response from server which says that "TCP Port numbers reused" and immediately after that router sends TCP RST signal to server.

What can be the problem and how to fix it?

[marce1000]

 - This thread is interesting , if the ISR behaves in the same way , it could be a probable cause :
        https://community.cisco.com/t5/application-networking/huge-connection-rst-after-put-ace4710-in-middle/td-p/2344451

 M.

[divas80]

I examined the capture file and did not find that the packet was somehow changed when traversing the router. I captured traffic on both the inside and outside interfaces and compared it. There was no such evidence, but I might be mistaken.

[MHM Cisco World]

can you share wireshark 

MHM

[divas80]

Please check.