diff --git a/certbot_dns_ionos/ionos.py b/certbot_dns_ionos/ionos.py
index 879835b..f6f377f 100644
--- a/certbot_dns_ionos/ionos.py
+++ b/certbot_dns_ionos/ionos.py
@@ -3,15 +3,13 @@
 import logging
 
 import requests
-from base64 import b64encode
 
 from certbot import errors
 from certbot.plugins import dns_common
-from certbot.plugins.dns_common import CredentialsConfiguration
 
 logger = logging.getLogger(__name__)
 
-dns_api_base_url = "https://dns.de-fra.ionos.com"
+dns_api_base_url = "https://dev.dns.de-fra.ionos.com"
 
 
 class Authenticator(dns_common.DNSAuthenticator):
@@ -19,7 +17,6 @@ class Authenticator(dns_common.DNSAuthenticator):
 
     This Authenticator uses the IONOS API to fulfill a dns-01 challenge.
     """
-
     def __init__(self, *args, **kwargs):
         super(Authenticator, self).__init__(*args, **kwargs)
         self.credentials = None
@@ -40,28 +37,10 @@ def more_info(self):  # pylint: disable=missing-docstring,no-self-use
     def _setup_credentials(self):
         self.credentials = self._configure_credentials(
             "credentials",
-            "IONOS API credentials INI file. Either basic authentication (username and password)" 
-            + "or a token should be provided.",
-            None,
-            validator=self._validate_credentials
+            "IONOS API credentials INI file. Only Bearer token authentication is supported",
+            {"token":"access token for the IONOS API"},
         )
 
-    def _validate_credentials(self, credentials: CredentialsConfiguration) -> None:
-        token = credentials.conf('token')
-        username = credentials.conf('username')
-        password = credentials.conf('password')
-    
-        if token:
-            if username or password:
-                raise errors.PluginError('{}: ionos_username and ionos_password are '
-                                            'not needed when using ionos_token'
-                                            .format(credentials.confobj.filename))
-        elif not username or not password:
-            raise errors.PluginError('{}:  ionos_username and ionos_password are required when '
-                                         'ionos_token is not provided'
-                                         .format(credentials.confobj.filename))
-        
-
     def _perform(self, domain, validation_name, validation):
         self._get_ionos_client().add_txt_record(
             domain, validation_name, validation
@@ -74,9 +53,7 @@ def _cleanup(self, domain, validation_name, validation):
 
     def _get_ionos_client(self):
         return _IONOSClient(
-            self.credentials.conf("token"),
-            self.credentials.conf("username"),
-            self.credentials.conf("password"),
+            self.credentials.conf("token")
         )
 
 
@@ -85,12 +62,9 @@ class _IONOSClient(object):
     Encapsulates all communication with the IONOS Cloud DNS API.
     """
 
-    def __init__(self, token, username, password):
+    def __init__(self, token:str):
         logger.debug("creating IONOS Client")
-        if token:
-            self.headers = {"Authorization": "Bearer " + token}
-        else:
-            self.headers = {"Authorization": "Basic " + b64encode(username+":"+password)}
+        self.headers = {"Authorization": "Bearer " + token}
 
         
     def _handle_response(self, resp: requests.Response):
@@ -105,9 +79,6 @@ def _handle_response(self, resp: requests.Response):
              "API response with non JSON: {0}".format(resp.text)
          )
 
-    def _get_url(self, action):
-        return "{0}?{1}".format(self.endpoint, action)
-
     def add_txt_record(self, domain, record_name, record_content):
         """
         Add a TXT record using the supplied information.
@@ -117,13 +88,14 @@ def add_txt_record(self, domain, record_name, record_content):
         :param str record_content: The record content (typically the challenge validation).
         :raises certbot.errors.PluginError: if an error occurs communicating with the IONOS API
         """
+        print("getting started")
         zone_id = self._find_zone_id(domain)
         if zone_id is None:
             raise errors.PluginError("Domain not known")
         logger.debug("domain found: %s with id: %s", domain, zone_id)
         record = self.get_existing_txt_acme_record(zone_id, record_name)
-        record_properties = record["properties"]
         if record is not None:
+            record_properties = record["properties"]
             if record_properties["content"] == record_content:
                 logger.info("already there, id {0}".format(record["id"]))
                 return
@@ -151,8 +123,8 @@ def del_txt_record(self, domain, record_name, record_content):
             raise errors.PluginError("Domain not known")
         logger.debug("domain found: %s with id: %s", domain, zone_id)
         record = self.get_existing_txt_acme_record(zone_id, record_name)
-        record_properties = record["properties"]
         if record is not None:
+            record_properties = record["properties"]
             if record_properties["content"] == record_content:
                 logger.debug("delete TXT record: %s", record["id"])
                 self._handle_response(