I looked for open source and free forums - and FluxBB I used in the Iinux CrunchBang days and liked it. And phpBB came up as well as an option which I've used on theWord website. And I like the old style as well. Both seem to have nice Dark themes availible as well. I was also looking for something that works well on mobile. In any case it takes time to dig around. But it is moving forward at least. Seems phpBB also has a very active user foundation.