In some cases, encrypted IPsec packets offloaded to NP6 processors may be larger than unencrypted packets. When this happens, the packets may be blocked or fragmented by the exiting IPsec VPN interface if the encrypted packet size exceeds the MTU value of the IPsec VPN interface. This can happen even if
mtu-override is enabled for the interface.
You can use the following option to allow offloaded IPsec packets that exceed the MTU value of the exiting interface to be allowed without fragmentation.
config system npu
set ipsec-mtu-override enable