Core issue
The issue possibly arises due to URG flags blocked by ASA, which is the default behaviour of the ASA.
Few proprietary softwares cannot fully load when traffic passes through the ASA.
Resolution
In order to resolve the issue, configure the urgent-flag allow command in the ASA:
hostname(config)#tcp-map < mss-map >
hostname(config-tcp-map)#urgent-flag allow
These commands configures the ASA to allow urgent-flag.
Note: If the URGENT flag is set, segments sent to the destination TCP have the urgent pointer set. The receiving TCP signals the urgent condition to the receiving process if the urgent pointer indicates that data, which precedes the urgent pointer, is not consumed by the receiving process. The purpose of urgent is to stimulate the receiver to process the urgent data and to indicate to the receiver when all the currently known urgent data has been received. The number of times the TCP signals urgent of the sending user is not necessarily equal to the number of times the receiving user is notified of the presence of urgent data.
