GlobalProtect slow performance with repeated log "ipsec decap: decrypt failed with result -9"?
5568
Created On 05/31/22 10:23 AM - Last Modified 12/02/24 20:51 PM
Symptom
After making a connection with GlobalProtect, the performance becomes slow, and the below message repeatedly comes up in PanGPS.log.
(P4600-T12392)Debug( 852): 04/12/22 08:27:37:365 ipsec decap: decrypt failed with result -9
Environment
GlobalProtect
Cause
The slow performance might be caused by the MTU (Maximum Transmission Unit) size. The default size of MTU for PANGP Virtual Adapter interface is 1400. Most of the users don't have this issue with this default setting. But some users need to adjust it due to the limitation of their Internet Service Provider or home network environment.
If the performance improves by setting the MTU to 1300, then it's due to the default MTU 1400 is too large for the user.
Resolution
To adjust MTU value on the GlobalProtect client device may fix the performance issue.
Please refer to HOW TO CHANGE MTU ON PANGP VIRTUAL ADAPTER USED BY GLOBALPROTECT APP for adjusting the MTU.
Also please refer to Configurable Maximum Transmission Unit for GlobalProtect Connections for setting MTU via GlobalProtect Portal Configuration.