Impact of Packet Fragmentation on Tunnel Stability
Maximum Transmission Unit (MTU) for a standard network interface is 1500 bytes. Additional tunneling protocol encryption takes up part of this volume for service data, causing ISP hardware to drop oversized packets without notifying the client.
How to Find and Fix MTU
- test the connection via the ping console command with fragmentation-prohibiting flags
- decrease the test packet size in steps of 10 bytes until packet loss completely disappears
- add 28 bytes of standard ICMP and IP headers to the resulting value
- set this calculated number in the MTU field of your VPN client config profile