SSH server rejected X11 forwarding request

Question

I have the following ...

ngDoCheck() {
    let changes = this.differ.diff( this.immunization )
    
    if ( changes ) {
      changes.forEachChangedItem( r => {
        /// previously worked API
        console.log( r.currentValue.keys )  /// does not work
        console.log( r.key )  /// does not work

        console.log( 'changes detected' )
        changes.forEachChangedItem( r => console.log( 'changed ', r.currentValue ) )      
      } )

//      changes.forEachChangedItem( ( elt ) => {
//        switch ( elt.key ) {
//          case 'disease':
//            console.log( 'Disease has changed' )
//        }
//
//      } )
    }
  }

I am attempting to get the key of the property that changes with the ngDoCheck(), but without much success in the code above. Any help is appreciated

EDIT 1

export class Immunization {
  disease: string
}

immunization = new Immunization() // r logs immunization property change

Solution

Just because I disable IPv6, I need to add AddressFamily inet to /etc/ssh/sshd_config., I was too careless before. I'm sorry.

The third answer: Link