I can NOT access the connected storage device with the correct authentication. It displays an error message on my iPhone®, The operation couldn't be completed. Invalid argument.
If an existing server is in the shared list, it needs to be removed. Only then can you re-connect to the server. The steps below will show you how to remove the existing server.
On your iPhone, open the Files app.
Under Shared, tap the eject icon beside the server's name.
After you re-connect to your server you should now be able to access the connected storage.