Slow speeds (<1mbit/s) only with some users

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  • pvalerio
    Junior Member
    • Jul 2024
    • 1

    Slow speeds (<1mbit/s) only with some users


    I'm running several OpenVPN servers which are used by about 1000 users.
    Specs: Debian 12, OpenVPN 2.6.11, AES-256-GCM, DCO enabled and TLS crypt v2. 3 instances on each server (UDP 1194, UDP 80, TCP 443).
    Clients are my own developed Swift apps for Apple devices using openvpn3 libraries (v3.8.4).
    The performance is very good, on my home 320 mbit/s connection I get about 310 using UDP and about 290 using TCP, even on very far servers.

    I have a handful of users though which get extremely slow speeds (DL under 1 mbit/s, UL 40 mbit/s) and I can't figure out why.
    I'm using MTU of 1400 for UDP and 1280 for TCP (set on both servers and clients), but even with lower MTU of 1100 the issue stays the same.
    I also implemented the obfuscation XOR patch, which together with TCP port 443 and TLS crypt v2 should circumvent provider throttling (in China it works fine).
    Still the issue is the same. If those users download a testfile from the same server though, the speed is fast.

    What else could I try?

    ca ca.crt
    cert server.crt
    crl-verify crl.pem
    dh dh.pem
    key server.key
    tls-crypt-v2 tc2.key
    cipher AES-256-GCM
    data-ciphers AES-256-GCM
    auth none
    topology subnet
    max-clients 250
    dev tun1
    port 1194
    proto udp
    push "redirect-gateway def1 bypass-dhcp"
    tun-mtu 1400
    push "explicit-exit-notify"
    keepalive 10 60
    reneg-sec 28800
    user nobody
    group nogroup
    sndbuf 0
    rcvbuf 0
    txqueuelen 1000
    verb 0
    mute 1
    log /dev/null
    status /dev/null
    Last edited by pvalerio; 2024-07-05, 02:43 PM.