Forticlient error Vpn Parameter Config Error

[andrejrepka20]

Hello,

I have encountered strange issue on our FortiClient configuration.

We have deployed FortiClient via EMS Cloud to 500+ stations and for some time everything runned smoothly but suddenly lot of stations started to disconnect with this error even tho the configuration on both sides remained unchanged.

The VPN connection is re-established randomly.

For the specific error - VpnParameterConfigError i did not find any community posts, I reviewed configuration on both sides as the error is pretty explanatory but did not find any misconfigurations.

As this is currently production environment, i cannot really troubleshoot this issue and make lot of changes on the current VPN configuration at the moment and need to wait for a weekend.

If anyone encountered this beforehand please shine some light on this issue.

Thank you

Below I attach screenshot from the FortiClient (its in Slovak as the customer has it set this way)

Rougly translates to: Last reason of disconnection: VpnParameterConfigError

[AEK]

Hi Andrej

What is the versions of FCT & FGT?

The description you provided (suddenly lot of stations started to disconnect) it like the issue is from FGT side.

As first step try check VPN logs from both FCT and FGT sides. They may provide some interesting info about the disconnection.

[andrejrepka20]

FGT is 7.4.7, FortiClient is 7.4.4,

In FGT logs I wasnt really able to pinpoint exactly what was causing the issue as there was multiple logs about tunnels going up/down and renegotiations, nothing above log level notice, only some esp_error logs.

I recieved DiagFile from customer from FCT but wasnt also able to detect any specific issue, probably needs to dig deeper