Iperf3 UDP Questions

Hi friends. I have a wireguard server on a Brume 2 and a wireguard client on my mobile SlateAX. I’m usnig iperf3 on both to test throughput speeds, and so far so good using basic settings.

However when I try to test UDP with the -u command, the client just sits there, and the server outputs a lot of zeros:

Any ideas why this is happening and how to fix it?

Does tcp work okay? How much is the throughput?

yep, TCP works fine (I assume since I’m running regular client mode -c). Throughput is around 50Mbps

My test is good, the wireguard server is in another city.
Could you please try to set MTU to a lower one, eg 1280, WireGuard Client Options.

ok i’m trying again tonight. here’s regular test from my windows PC to wireguard server on Brume 2: ./iperf3 -c #####.glddns.com

Here’s when running the UDP command: ./iperf3 -c ######.glddns.com -u

Here’s the view from the server during UDP attempt:

I’ve set my MTU to 1420, same results

Before adjusting the MTU system wide, you can try to adjust the packet send by iperf3 with --length 128 (very small, but should definitely not fragment).