Technical Tip: How to adjust the Maximum Transmission Unit (MTU) value for FortiClient SSL VPN Virtual Ethernet Adapter

[volkanavsar]

Description	This article describes how to change the MTU value for the FortiClient SSL VPN Virtual Ethernet Adapter.
Scope	FortiClient, FortiClient EMS.
Solution	Using FortiClient v7.2.9 and v7.4.3 and above, FortiClient SSL VPN Virtual Ethernet Adapter MTU value changing is possible. It can be modified using 'Remote Access Profile XML' as follows. <vpn> <sslvpn> <options> <mtu_size>1392</mtu_size> After successfully connecting to the VPN tunnels, the value of the virtual adapter is expected to change accordingly. The command 'netsh interface ipv4 show subinterfaces' in PowerShell can be executed to verify this change. It can also be verified by looking at the value in the: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ftsvnic\MTU