@girish Thank you. The Red Hat documentation was roughly how I was thinking of it and in that case I should be fine with 1GB of swap (as I am not suspending the server, etc...) although 2GB might be better.
However, if i look at my apps they say, "Cloudron allocates 50% of this value as RAM and 50% as swap.". If that is a hard rule then that might explain why my apps seem to be restarting, even ones that don't get a huge amount of load (eg; low visit website), as after 8 x 256mb apps my swap space is fully allocated.
Now, I am running 17 apps at the moment and according to System Info/System Memory this is using 3GB of memory out of "RAM (3.85 GB) + Swap (984.99 MB)" which would seem to me to be a reasonable headroom unless the swap rule is hard at which point I have (assuming 256mb apps) over 2GB allocated to swap and under 1GB available.
So, is the swap rule hard? Because then it would seem to me to mean I need to have the same amount of swap as RAM. In my case 4GB.
Hopefully that is clear and thank you for your former reply.