Create Local Firewall Rule, Inbound Port 6443 to ArcGIS Server

Allow inbound port 6443 traffic to the ArcGIS Server

Before configuring server federation within Portal for ArcGIS, first you need to create a local firewall rule to allow inbound port 6443 traffic to the ArcGIS Server:

Open Windows Defender Firewall with Advanced Security.
Right-click Inbound Rules and select New Rule.
For Rule Type, select Port. Click Next.
For Protocol and Ports, select TCP, then select Specific local ports and type 6443 in the field. Click Next.
For Action, select Allow the connection. Click Next.
For Profile, select when the rule should apply. Typically Domain is selected as most utilities are connected to a corporate domain, but select Private if you’re setting this up for a home network. Click Next.
Type a descriptive name for the rule, an optional description, and click Finish.