On some occasions, you might see a lot of retransmissions or CRC errors leading, after a while, to a dropped X.25 connection with the following error :
"Network Operation Did Not Complete in a Reasonable Amount of Time."
A connection through X.25 relies on the XPC protocol. The following NOTES.INI variable : XPC_Enh_Format_Off=1 allows using a smaller XPC packet size.
Note: This variable must be set on both sides. Even if some retransmission or CRC errors are still present, the communication usually completes.
Disabling data compression on the modem is another way of improving the communication.