Ark server isn't updating after the last patch 2 days ago resulting in not being able to connect to server that is out of date? It this poor service pretty common with these guys?

The Linux version of ARK Server is currently 315.9, and has been for a while now. The server version number is an arbitrary label manually affixed by the developer who bakes the update in the devkit before pushing it to the master file. Often times the guy who does the incrementing of that number for WildCard forgets to increase the Linux version.

I rent two servers from this host, and run a personal Linux and Windows server from my home. I am able to connect and play on both rental servers. One with a total of 23 mods, running many of the top 20 mods. The other completely vanilla. I am able to play on both of my local servers. The Linux version on my local server is also 315.9, and I can confirm it's the most recent build from SteamCD.

If you're not able to connect, then there is most likely a technical issue with the install (do a server rebuild), configuration, or local client (verify your local files), and you'll need to either submit an email ticket for resolution or possibly submit here what errors you're receiving so community members can assist.