Sync without Internet Question

I am trying to setup my Plex server to allow syncing to devices but access to an internet connection will be severely limited. My setup is currently as follows:

  1. Intel NUC with Plex Media Server (remote access is disabled)
  2. 802.11ac wireless router (Plex server has a wired connection)
  3. Company Network (with SOCKS4 proxy, Intel NUC has Proxifier installed and configured to route all traffic through proxy)

With this setup my Plex Media server is able to connect and receive metadata updates, it also shows my Plex Pass account as signed in. The client devices which connect to the 802.11ac router and access the private network it establishes are able to access the Plex Server using iOS and Android Plex apps and stream media. When attempting to setup a sync the process appears to fail. Looking on the Plex Media Server i see no new authorized devices appearing. I have configured the Plex Media Server to allow the entire private network subnet to access the server with authorization requests.

The major cavet with my setup is that the iOS and Andriod devices will not have an internet connection when connected to the private network, only the Plex Media Server has an Internet Connection.

Is there any way to configure my setup to allow syncing to occur?