You're listed at https://iperf.fr/iperf-servers.php as running one. And I'd say HE is the most recognizable and trusted name on that list.
But the iperf3 server is down right now I think:
root@UR:~# iperf3 -c iperf.he.net
iperf3: error - unable to connect to server: Connection refused
Has it been replaced with something newer/better?
This forum is listed as the contact link on iperf.fr, so I'm reaching out this way.
iperf3 was designed to only allow a single connection to the service, in order to have it have the maximum bandwidth available for a test, and not compete with other connections. If you're seeing connection refused, it means someone else is currently using the service.