On the 11th June 2018, OVH massively dropped prices on their ARM-based SoYouStart storage servers. To people looking for a cheap dedicated server, these offers are very attractive as for just £5.99 per month, you can get a server with a 2TB hard drive and an unmetered 250Mbps connection.
Unfortunately, when users ordered these servers they found that outgoing was limited to 5Mbps on single threaded tests, this problem was caused by a driver bug.
On the popular web hosting forum Lowendtalk, the user K4Y5 posted some simple to follow commands for Debian 9 that will fully solve this problem:
apt install linux-image-4.9.0-6-armmp linux-headers-4.9.0-6-armmp
apt purge *armada*
reboot
After inputting these commands and installing the replacement kernel, your server should be able to upload at the advertised speed.
Servers affected: ARM-2T, ARM-4T, ARM-6T