We have a few applications that we develop in my company that talk to some hardware via UDP. Recently, we started having issues using these applications on some of our machines (hardware basically refusing the connection with the client).
After investigation, we noticed that duplicated UDP packets are being sent out.
As an example, this is a UDP datagram sent on a healthy machine (using WireShark):
This is the duplication on one of the faulty machines:
A pcapng file from Wireshark can be found here (look for DNS request from client machine 10.0.9.183).
There are a few things we can rule out:
- We know this is not an issue with our apps, as even DNS sends duplicated packets. I used this script to send simple UDP datagram and we saw a similar behaviour (see screenshots above)
- We know this is not a network interface fault, as on a faulty machine, duplicated packets are sent via WiFi, Ethernet, USB-Ethernet adapters etc.
- We know this is not one particular switch/router that is dodgy as this happens in the office, from home (with and without VPN)
- Some machines work just fine, some don't. They all run Windows10 (same exact version).
It has to be something wrong with the machine but I have really no idea what to try to fix this. I have updated some of the networking interfaces' drivers on this machine + rolled out a Windows10 update but nothing seemed to fix it.
Of course, a possible fix would be to re-program the hardware such that it knows how to deal with duplicated packets, but we really want to be able to get to the bottom of this and fully understand what is causing the issue.
I'm not a network expert at all, hence me posting this here. Is this behaviour something somewhat common and what could possibly cause this?
Many thanks
