Troubleshooting Tip: Error 'object set operator error,-54' while configuring 'mtu-override' option in the IPsec interface

[vinodhini]

Description	This article explains how to avoid an error, 'object set operator error, -54', while configuring mtu-override in the IPsec interface.
Scope	FortiGate v7.4.
Solution	To check the current MTU value of the Interface on FortiGate, use any one commands: diagnose netlink interface list <intf_name> fnsysctl ifconfig <intf_name> For this example, use 'diagnose netlink interface list vpn-ipsec' or 'fnsysctl ifconfig vpn-ipsec'.   When configuring the mtu-override option in the IPsec VPN interface, it shows the following error: FGT #config system interface FGT (interface) # edit vpn-ipsec FGT (vpn-ipsec) # set mtu-override enable FGT (vpn-ipsec) # set mtu 1340 FGT (vpn-ipsec) # next object set operator error, -54 discard the setting Command fail. Return code 1 FGT (interface) #  This error appears when the VPN interface has IP and remote-ip configured. Removing the IP and remote-ip in the vpn interface configuration would resolve the issue. config system interface     edit vpn-ipsec         unset ip         unset remote-ip         set mtu-override enable         set mtu 1340     next end Related articles : Technical Tip: MTU size and Interface related Errors on FortiGate Technical Tip: How to adjust the Maximum Transmission Unit (MTU) value