What could be the reasons for the low connection speed?

Question

Server equipment

I bought myself a VPS, but I ran into a problem that the speed in both directions is low, less than 1Kb / s. Technical support unsubscribed that everything is fine on their part, the channel should be 100Mb. The system is almost clean, ubunta. Only nginx is installed, nothing has been configured yet. What could be the problem?
Question number two - how can I monitor the speed to the site from the outside? From the server, let's say I can pull something heavy along the crown and write to the log, but how back? Is there any service?

Answer 1

iperf?
iperf is installed on the server and locally.
on the server iperf -s, locally iperf -c 111.111.222.333 (server IP).
Testing in both directions, options are described in the mana.
Not quite on the issue, of course, but at least check the channel to the server.