My experience on v6.4.6 upgrade was a nightmare. Have been using v6.4.3 since Dec.2020 and absolutely no issues. We have 3 Internet links and configured with SD-WAN 2 years ago. Upgraded to v6.4.6 on 22-Jul-2021 and have reported issues across different office locations of connection getting dropped intermittently. Raised TAC with Fortinet and they have confirmed bug as may of their customer reported issues when they are working on Latency sensitive applications like MS-Teams, Citrix, Office365 which is similar to my issue. I have rolled back to v6.4.3 and will wait until the v6.4.7 is released.
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