Core issue
This problem can occur when ,
a) The community string is not configured properly
b) ACL filtering .
Resolution
For a workaround,
a) First check whether proper community strings have been configured. If not follow the steps given below,
- Go to Configuration > System > Management Protocols > SNMP Communities.
- Click the Add button to add a community string.
- Add the desired community string, for example "public".
Try to access the VPN concentrator after these steps are performed. Ideally, it should function properly now.
If the VPN concentrator still does not work,
b) Make sure that the Access Control List (ACL) does not block the PC from which the attempt to access the concentrator originates.
Note: SNMP is used only to monitor the VPN concentrator, not for configuration purposes.