TCP MSS (Maximum Segment Size): The maximum size of the data segment of a TCP packet can be transmitted at a time. For some data that meet certain conditions, Network Secure supports changing the TCP MSS values of such data packets. This function is used to adapt the device to a more complicated network environment. It is advised to enable it when necessary.

Navigate to Network > Advanced > TCP MSS, check Enable to enable TCP MSS configuration, and click Add to add a rule.

Name: Set the rule name.

Description: Set the description of the rule.

MSS: Set the TCP MSS value that needs to be specified.

Src Address/Src Port: Set the source IP group and source port, and specify the source conditions that match this rule.

Dst Address/Dst Port: Set the destination IP group and destination port, and specify the destination conditions matching this rule.