1. I used to see this mainly on WAN connections. The connection times out before all the encapsulation characters are received. The driver expects to see both beginning and ending encapsulation before the timeout is reached. The standard mpl-tcp pdl uses <0b> as the beginning characters and <1c0d> as the ending characters.
2. The encapsulation does not match what the driver expects to see.
To check, turn up EO and review the log. When EO is enable all you can see the encapsulation characters in the log file. Most of the time the message makes it within the timeout but when it doesn’t it puts the no match no phrases error in the log. If the encapsulation is correct then it is more than likely a timeout issue. If it doesn’t match then you will need to modify the pdl or have the vendor change their side.
If it is timing out you are in luck. There is a pdl in the tcl section of this board that you can download that has a timeout of 60 seconds built in. This pdl uses standard <0b><1c0d> encapsulation.