Getting the error rhn-plugin: Error communicating with server. The message was: Forbidden

rhn-plugin: Error communicating with server. The message was:
Forbidden

Trying to register to Nagra server and getting below error :
My IP is already whitelisted.

System : Centos 7 using on Oracle VM virtual Box

[Wed Mar 20 15:32:25 2024] up2date A protocol error occurred: Forbidden , attempt #1,
[Wed Mar 20 15:32:25 2024] up2date
Traceback (most recent call last):
File "/sbin/rhnreg_ks", line 218, in <module>
cli.run()
File "/usr/share/rhn/up2date_client/rhncli.py", line 96, in run
sys.exit(self.main() or 0)
File "/sbin/rhnreg_ks", line 90, in main
rhnreg.getCaps()
File "/usr/share/rhn/up2date_client/rhnreg.py", line 248, in getCaps
s.capabilities.validate()
File "/usr/share/rhn/up2date_client/rhnserver.py", line 178, in __get_capabilities
self.registration.welcome_message()
File "/usr/share/rhn/up2date_client/rhnserver.py", line 63, in __call__
return rpcServer.doCall(method, *args, **kwargs)
File "/usr/share/rhn/up2date_client/rpcServer.py", line 203, in doCall
ret = method(*args, **kwargs)
File "/usr/lib64/python2.7/xmlrpclib.py", line 1233, in __call__
return self.__send(self.__name, args)
File "/usr/share/rhn/up2date_client/rpcServer.py", line 37, in _request1
ret = self._request(methodname, params)
File "/usr/lib/python2.7/site-packages/rhn/rpclib.py", line 384, in _request
self._handler, request, verbose=self._verbose)
File "/usr/lib/python2.7/site-packages/rhn/transports.py", line 170, in request
headers, fd = req.send_http(host, handler)
File "/usr/lib/python2.7/site-packages/rhn/transports.py", line 729, in send_http
response.status, response.reason, response.msg)
<class 'up2date_client.up2dateErrors.CommunicationError'>: rhn-plugin: Error communicating with server. The message was:
Forbidden