1. (node ​​we manage from) copy Public Key to Admin Key field in target node we will manage
2. (node ​​we manage) copy Public Key from managed node to Admin Key of node we will manage
3. admin channel is no longer needed
4.  

it is a type of exchange of public keys and entering them into the Admin Key fields between nodes

Not working? remove (from admin perspective) managed node from node list, and wait for reappear, restart nodes.

Tip: You can set same Public key and Private key on each node (then Public Key an Admin Key will be same values, don't forget to copy prv key)

Tip: Admin key is public key of managed node (or node, admin node), it means "allow manage by admin that identifies by that public key"