What is the best way to find a minecraft version that is compatible with all your mods on forge?

I am putting together a server for some friends and we want to use a custom modpack. I am having trouble finding a minecraft and forge version that works with all the mods. My assumption was that it a mod worked with 1.15 it would work with 1.14 but that doesn’t always seem to be the case. Does anyone have a good way of finding out a minecraft and forge version that will work with a list of mods?