Switch Ubuntu Linux kernel on OVH Dedicated Gaming Servers

I've been recently working on multiple large-scale Minecraft servers. We use dedicated gaming servers from OVH and it's so far so good, expect some small issues.

First, I needed to disable IPv6. It have been causing issues with my Docker setup and it, frankly, often fails. I tried to modify sysctl values or even GRUB start cmd to attempt to disable it, but they don't seem to work. After some time I realised that the server, in default, is running a custom OVH kernel, which seems to force enable IPv6. So very obviously I had to switch to a stock kernel.

So as usual, you switch kernel using apt install linux-image-xxx. But it didn't work either. I messed around with GRUB settings and after a couple of hours nothing seems to be working. I went to OVH panel to check the boot settings and realised that OVH dedicated servers, by default, uses netboot to boot the servers. Not sure why, but switching it to hard disk boot solved everything.

OVH dedicated servers is full of tricky issues that frusturates me very often. For example, most of the storage is by default given to /home, 400+ GB, in my case, and 20 GB for /. What the hell, OVH?

By the way, don't use their default DNS for the Docker daemon... It takes a million year to resolve a single hostname.