Cannot connect to service - Centos 7

Three solid days trying to diagnose this and I'm fried.

I'm trying to install R and RStudio-server on a Centos 7 machine. I had an old install and (stupidly) manually deleted files to completely purge my system. Bad idea I know (now).

I deleted the rest of the description because it was a rabbit hole I don't wish on anyone. To resolve I removed everything via yum then followed these instructions. Works like a charm. and