I had a scanner installed and we use these to scan to email using obviously via SMTP. It would not scan an actual scanned document but the the device has an SMTP test that would send a small emails and so it would complete the communication. I was told by the tech that the reason was that the MTU size was an issue. I was also told that the carrier "Wireless 4G LTE" was the root cause of the issue and when using "tunnel path-mtu-discovery" I'm told that " , the carrier isn’t sending the ICMP Packet Too Big Messages back to our router" I have a packet capture during this scanning process, my question is how can I tell that this is the case?
