This is a call for help. I am having headaches with OpenVPN client-server thoroughput on MikroTik's baby RB750. Client->server traffic is like ~13KB/s maximum and server->client ~25KB/s maximum. The usual sustained speeds are at about half of the max figures. In a word, beyond horrible. All aspects of vpn connection are tolerable, except the speed.
Being relatively new to RouterOS world I am struggling to figure out what may be causing the problem.
-> Configuration based on MikroTik Wiki recommendation, TAP method in use (have tried TUN mode briefly but wasn't any better performance wise)
-> Server is managed fully by RouterOS
-> Clients are OpenVPN installation v2.1.1 (older been tested too) on Windows (XP, Vista, 7)
-> LAN segment is 192.168.2.0/24, VPN segment is 192.168.3.0/24, bridged
-> No packet loss occure in VPN communication
-> Went through RouterOS 4.0 to 4.4 upgrades, problem remains
-> CPU load is low during VPN sessions (CPU is not the bottleneck here)
Here's an interesting observation:
1. VPN connections initiated from LAN do perform nicely and the thoroughput is limited purely by CPU, thus ~3MB/s at average depending on encryption method used. VPN connection initiated from WAN are crippled as stated above.
2. Changing encryption method doesn't solve the problem (blowfish, aes, no encryption, ...).
3. Changing MTU in server and client configs doesn't solve the problem.
4. Switching SRC NAT off (to rule out possible interference) doesn't solve the problem.
5. No useful information is noted in client and server logs.
Would you recommend trying downgrade to v3, does it worth the hassle?
This is just a brief description, I may post further configuration details later.
Thanks for any hints