All network rules and access rules are configured using Identify Provider Discovery. Ensure your Identity provider has on-prem IWA Desktop SSO. See Configuration in Identity Provider Routing Rules.
If you turn off IWA DSSO, the IWA Routing Rule will be switched to Inactive. The next Routing Rule will be used to direct your users to the appropriate sign in. When you turn IWA DSSO on again, you must also switch the IWA Routing Rule to Active again.