Test your server's network
Measure latency, packet loss and throughput between your computer and your server with ping, mtr and iperf3, and what to send us if it looks wrong.
When a server feels slow over the network, measure before you guess. Three tools between them tell you whether it's latency, packet loss or bandwidth, and roughly where along the path it starts.
203.0.113.42 and 2001:db8:9::2 stand in for your server. Test only between machines you control; load-testing or scanning other people's hosts breaks the Acceptable Use Policy.
Latency with ping
From your computer:
ping -c 20 203.0.113.42
ping -6 -c 20 2001:db8:9::2(On Windows, ping -n 20 203.0.113.42.)
The last lines give packet loss and round-trip times as min/avg/max/mdev. You want 0% loss. The average mostly reflects physical distance, so a server far away will always show a higher number. mdev is jitter, and it should be small next to the average.
The path with mtr
mtr is ping and traceroute in one, so you can see the hop where trouble starts. On Ubuntu or Debian, apt install -y mtr-tiny; on a Mac, brew install mtr.
mtr -rwzc 100 203.0.113.42That sends 100 probes (-c 100), prints a report (-r), keeps host names whole (-w) and shows which network each hop belongs to (-z).
Reading the report trips people up, so:
- Loss on a hop in the middle that doesn't carry on to the last line is normal. Lots of routers are slow to answer probes on purpose, while forwarding your real traffic just fine.
- Loss that starts at one hop and continues to the end is real. That hop is where it begins.
- A jump in latency that stays for every hop after it is usually just distance, not a fault.
Run it both ways if you can: from you to the server, and from the server back to your public address. Internet routes are often different in each direction.
Throughput with iperf3
Install iperf3 on both ends with apt install -y iperf3. If it asks whether to start it as a daemon, say No.
On the server, open the port and start a listener that quits after one test:
ufw allow 5201/tcp
iperf3 -s -1From your computer:
iperf3 -c 203.0.113.42 -t 20
iperf3 -c 203.0.113.42 -t 20 -RThe first measures upload to the server, the second (-R) download from it. -P 4 runs four streams at once, closer to what a browser or download manager does. Close the port afterwards with ufw delete allow 5201/tcp.
Keep in mind the result can't beat the slowest link on the path, and that's often your own connection or Wi-Fi. To test the server's connection itself, run the client from another well-connected server.
If the network checks out but the site is still slow, the bottleneck is probably on the server: see Monitor your server, and confirm the service is listening where you think with ss -tlpn.
Sending it to us
If something looks wrong on our side, open a support ticket with the mtr reports from both directions (as text, not screenshots), the iperf3 numbers if it's a speed problem, your server's address, and when it started. That's usually enough for us to say whether it's our network, something in between, or your end.