The Federated Cloud ID showing as hooni@http://192.168.55.28 instead of a proper domain-based ID is expected when you access Nextcloud by IP address without a domain name configured.
The Federated Cloud ID is derived from the overwrite.cli.url setting in your Nextcloud config. Since you are connecting directly by IP, Nextcloud uses that IP as the server identifier.
To fix it, edit your config.php (for Snap installs it is at /var/snap/nextcloud/current/nextcloud/config/config.php) and set:
'overwrite.cli.url' => 'https://cloud.yourdomain.com',
'overwritehost' => 'cloud.yourdomain.com',
'overwriteprotocol' => 'https',
This changes the Federated Cloud ID to hooni@cloud.yourdomain.com which is the correct format for federation to work with other Nextcloud instances.
If you are just testing locally without a domain, federation will not work properly with an IP address anyway since remote Nextcloud servers need to be able to reach your server by hostname and verify it. For local testing between two Nextcloud instances on the same LAN, you can use /etc/hosts entries on both machines to give each server a hostname, then configure overwrite.cli.url accordingly.
Also make sure the hostname you choose is listed in the trusted_domains array in the same config.php file.