diff --git a/influxdb_client_3/write_client/_sync/rest_client.py b/influxdb_client_3/write_client/_sync/rest_client.py
index 76afba9..3516029 100644
--- a/influxdb_client_3/write_client/_sync/rest_client.py
+++ b/influxdb_client_3/write_client/_sync/rest_client.py
@@ -8,7 +8,7 @@
 import ssl
 import sys
 from typing import Dict
-from urllib.parse import urlencode
+from urllib.parse import urlencode, urljoin
 
 from influxdb_client_3.write_client.rest import ApiException
 
@@ -121,7 +121,7 @@ def __init__(self,
                 proxy_headers=proxy_headers,
                 ssl_context=ssl_context,
                 **addition_pool_args
-            ).connection_from_url(url=base_url)
+            )
         else:
             self.pool_manager = urllib3.PoolManager(
                 num_pools=pools_size,
@@ -133,7 +133,7 @@ def __init__(self,
                 key_password=cert_key_password,
                 ssl_context=ssl_context,
                 **addition_pool_args
-            ).connection_from_url(url=base_url)
+            )
 
     def request(self, method, url, query_params=None, headers=None,
                 body=None, timeout=None, **urlopen_kw):
@@ -152,8 +152,10 @@ def request(self, method, url, query_params=None, headers=None,
                            :meth:`urllib3.request.RequestMethods.request`
         """
 
+        # Keep support for absolute URLs while constructing full URLs for relative paths.
+        request_url = url if url.startswith(("http://", "https://")) else urljoin(self.base_url, url)
         if query_params:
-            url += '?' + urlencode(query_params)
+            request_url += '?' + urlencode(query_params)
 
         merged_headers = {}
         if self.default_header:
@@ -164,13 +166,13 @@ def request(self, method, url, query_params=None, headers=None,
         effective_timeout = timeout if timeout is not None else self.timeout
 
         if self.debug:
-            RestClient.log_request(method, url)
+            RestClient.log_request(method, request_url)
             RestClient.log_headers(merged_headers, '>>>')
             RestClient.log_body(body, '>>>')
 
         try:
             r = self.pool_manager.request(
-                method, url,
+                method, request_url,
                 body=body,
                 headers=merged_headers,
                 timeout=effective_timeout,
diff --git a/tests/test_write_api.py b/tests/test_write_api.py
index 7c04385..a1fe40a 100644
--- a/tests/test_write_api.py
+++ b/tests/test_write_api.py
@@ -11,6 +11,7 @@
 from influxdb_client_3 import InfluxDBClient3, InfluxDBError
 from influxdb_client_3.exceptions import InfluxDBPartialWriteError
 from influxdb_client_3.version import VERSION
+from influxdb_client_3.write_client._sync.rest_client import RestClient
 from influxdb_client_3.write_client.rest import ApiException
 
 _package = "influxdb3-python"
@@ -295,6 +296,21 @@ def test_request_arg_timeout(self, mock_request):
         self.assertEqual(0.1, self.received_timeout_total)
         self.received_timeout_total = None
 
+    @mock.patch("influxdb_client_3.write_client._sync.rest_client.urllib3.ProxyManager")
+    def test_rest_client_proxy_uses_proxy_manager_instance(self, proxy_manager_cls):
+        manager = mock.Mock()
+        manager.request.return_value = response.HTTPResponse(status=200, reason='OK', headers={}, body=b'')
+        proxy_manager_cls.return_value = manager
+
+        rest = RestClient(base_url='http://localhost:8181', proxy='http://proxy:3128')
+        self.assertIs(rest.pool_manager, manager)
+
+        rest.request(method='GET', url='/ping')
+
+        manager.request.assert_called_once()
+        args, _ = manager.request.call_args
+        self.assertEqual(('GET', 'http://localhost:8181/ping'), args[:2])
+
     def test_should_gzip(self):
         client = InfluxDBClient3(
             host='http://localhost:8181',