Fortios 5.4 ,5.2 forticlient VPN

Hi,

Recently I discover some problems whit connection via forticlient IPSEC VPN to my head office network.

When new users is connecting whit succes, the existing connections "freeze" for few secodns especially RDP services. In that time ping is jumping form 12ms do 400-600ms, and after few jumps back tu normal state. The same thing is happens when client is disconnecting.

Can you help me to resolve that problem ?

Fortios 5.4, FGT200D, Forticlient 5.4 5.2.

Regrads

Chris