I have the same problem and haven't found an answer yet.
The Problem: aliases and symlinks on the server are disabled in file dialogs for apps running from clients. Sole exception I've found is Apple's TextEdit on client, which can navigate through aliases that are on the server (with file dialog for open but not for save). Every other app, apple and otherwise, that I've tried on clients, including latest Apple Pages (version 7.1 (5683)) and Safari (Version 11.1.2 (13605.3.8)), find aliases on the server to be greyed out and disabled in file dialog windows, for both open and save. Aliases on the server work fine when double-clicked in Finder by clients.
This happens on server running macOS Sierra (10.12.6) with Server.app 5.3.1, and on server running macOS High Sierra (10.13.6) with Server.app 5.6.1.
Client macs are all running macOS High Sierra (10.13.6).
Things that work:
- An alias that is ON the client can point to a file on the server: apps on the client such as pages can use that alias in a file dialog to get to the remote folder.
- An alias that is on the server can be used in file dialogs by apps on the server.
My tests so far:
- From client mac, make alias on the server for a folder on the server. Pages and Safari on client find that alias grey (unusable) in file dialog.
- On server, make alias on the server for a folder on the server. Safari on server can follow the alias (which appears active, not grey) in a file dialog. Safari on a client can NOT follow the alias, which appears grey and unusable in file dialog.