If you login to SSH and run "free -m", and get:
Swap: 0 0 0
This means that your swapfile is not being mounted correctly on boot, it's most likely missing from /etc/fstab. Sometimes it can be omitted during the build process.
Please initially try a Reboot via SolusVM as it should (in theory) correct this automatically.
If not, see below:
Run "fdisk -l" so you can see all of the partitions/volumes on your system.
Identify which is your swap by the capacity, it's usually /dev/sda2
Now, open up /etc/fstab with "nano /etc/fstab" and add the following line under the other lines:
/dev/sda2 none swap sw 0 0
Substitute /dev/sda2 with the relavent volume, save and reboot.
