Sometimes you will get this kind of issue but how to find this issue existing in your net work could be a bit trick. Because normally people will think this problem could happen in LAN.
Such as for my case, we see one sever SSH access suddenly not working with this error : “Write Failed:Broken Pipe”, this looks like my years ago experience with similar issue.
At your linux – Ubuntu, you use a tool called arp-scan:
sudo apt-get install arp-scan
This command will show IP addresses, MAC address and manufacturer of the NIC. The line in the output that is a duplicate also identifies itself with a (DUP: 2)
sudo arp-scan -I eth0 -l
You can grep out part you have interesting to deal with it.