Need to make IpSec vpn connection more stable

Hello,

We are running fortigate VM. The problem is that IPsec VPN is not stable for some users and they get disconnects. It affects about 10-15 percent of users. From what I research i found out that the disconnect happens when a duplicate tunnel is created. That causes the tunnel shutdown and user has to reenter his FortiToken code. The main thing I would like to improve is to use IKEv2 with FortiToken(Xauth). Currently we have IkeV1 with aggresive mode which from my understanding is deprecated. The question would be is it posible to use IKEv2 and use FortiToken because GUI does not have that option and if possible how to set it up? We are running Forti OS 7.2.11.