What's new

OpenVPN Bandwidth tweaking

  • SNBForums Code of Conduct

    SNBForums is a community for everyone, no matter what their level of experience.

    Please be tolerant and patient of others, especially newcomers. We are all here to share and learn!

    The rules are simple: Be patient, be nice, be helpful or be gone!


New Around Here
Hi all,

we are searching some tips or advices about vpn speed.

we try to connect 2 networks with OpenVPN in site to site connection. 1 router is a RT-AX88U (3004.388.4), the other one is an OpnSense router.
Both sites have 1Gb/s fiber connection but the bandwidth throught VPN is limited to ~40Mb/s.

We have tried hard to have successful connection but we need a better speed.
We tried a speed test with iperf. 440Mb/s with direct connection via Internet with a port forwarding. 40Mb/s throught OpenVPN.

The configuration is as follow :
Auth Mode with Static Key
KEys and certificates generated by AsusMerlin router.
HMAC : Auth SHA 256
Cipher : AES-128-CBC
Compression : LZO

Custom conf :
sndbuf 0 (also pushed)
rcvbuf 0 (also pushed)

Is someone as tips to have a better speed.


Also use AES-128-GCM - saves a bit of overhead as it won`t require a separate SHA hash.
Custom conf :
sndbuf 0 (also pushed)
rcvbuf 0 (also pushed)
Maybe you can try:

data-ciphers AES-128-GCM:CHACHA20-POLY1305
data-ciphers-fallback AES-128-GCM
thanks we will try it.
GCM seems to be not supported. VPN server won't start and system logs says that
Dec 4 18:02:00 ovpn-server2[4086]: Cipher 'AES-128-GCM' mode not supported
Dec 4 18:02:00 ovpn-server2[4086]: Exiting due to fatal error

Perhaps we can add it by side.
Last edited:
Asus GT-AXE16000

my speed is only 200Mbit/sec.
If I read correctly, it should know 250 Mbit/sec.

Did I set everything up correctly?

Data ciphers: AES-128-GCM:AES-256-GCM:AES-256-CBC:AES-128-CBC:CHACHA20-POLY1305
THX :)

my speed is only 200Mbit/sec.
If I read correctly, it should know 250 Mbit/sec.
Not every server will be able to hit the theorical limit. If you get 200+, then you are within the expected range.
Yes, 'up to'.

Similar threads

Latest threads

Sign Up For SNBForums Daily Digest

Get an update of what's new every day delivered to your mailbox. Sign up here!