Unable to Connect to Server

[SylenThunder]

The first on is vanilla and is on 26905 and the second is a romero server with other addons and its on 26908. 

This is part of your issue.  The servers need to be 5 apart.  Even though the server is only slated for using 26900-26902, if it doesn't have 26903 it won't function. Leave the extra port open for a gap, and then next usable port is 26905.  In your case you're starting at 26905, so your Romero server needs to be at 206910. I mean you could stick it on 26909, but then you get odd port numberings, and it's harder to keep track of things.  

Disabling LiteNetLib will have a negative impact on your servers network performance. Clients will get out of sync easily.  SteamNetworking is basically used to trigger UPnP for opening ports. If you have proper forwarding it should be disabled. If you are unable to manually forward, or are behind a double-NAT, then you want to enable it.