No Server Response when using Proxy

[FuckingToasters]

Overview
Below you'll see a bug report about two different issues which both are the result of using a proxy.

First Issue
When requesting the Discord API with proxies using httpx.Client() after some time this issue happen:

Traceback (most recent call last):
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 60, in map_httpcore_exceptions
    yield
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 218, in handle_request
    resp = self._pool.handle_request(req)
  File "/usr/local/lib/python3.9/dist-packages/httpcore/_sync/connection_pool.py", line 253, in handle_request
    raise exc
  File "/usr/local/lib/python3.9/dist-packages/httpcore/_sync/connection_pool.py", line 237, in handle_request
    response = connection.handle_request(request)
  File "/usr/local/lib/python3.9/dist-packages/httpcore/_sync/http_proxy.py", line 267, in handle_request
    raise ProxyError(msg)
httpcore.ProxyError: 502 Bad Gateway

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/lib/python3.9/threading.py", line 954, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.9/threading.py", line 892, in run
    self._target(*self._args, **self._kwargs)
  File "/home/admin/bot/main.py", line 170, in verify
    VERIFYCODE = waitsms()
  File "/home/admin/bot/main.py", line 155, in waitsms
    discordresponse = client.post(discordurl, json=data, headers=HEADERS)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 1130, in post
    return self.request(
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 815, in request
    return self.send(request, auth=auth, follow_redirects=follow_redirects)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 902, in send
    response = self._send_handling_auth(
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 930, in _send_handling_auth
    response = self._send_handling_redirects(
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 967, in _send_handling_redirects
    response = self._send_single_request(request)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_client.py", line 1003, in _send_single_request
    response = transport.handle_request(request)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 218, in handle_request
    resp = self._pool.handle_request(req)
  File "/usr/lib/python3.9/contextlib.py", line 135, in __exit__
    self.gen.throw(type, value, traceback)
  File "/usr/local/lib/python3.9/dist-packages/httpx/_transports/default.py", line 77, in map_httpcore_exceptions
    raise mapped_exc(message) from exc
httpx.ProxyError: 502 Bad Gateway

Second Issue
Sometimes after some time, instead of the 502 error above, another issue appear:
Server closed without sending response`
(Currently i don't have the full Traceback for this issue ready to include here)

To Reproduce
Do a http request to discord.com while using proxies:

    data1 = {"foo": "bar"}
    with httpx.Client(headers=HEADERS, timeout=timeout, proxies=proxyauth if proxytype != "" else None) as client:
        resp2 = client.post("https://discord.com/api/v9/users/@me", json=data1)
    lock.acquire()
    if resp2.status_code == 204: pystyle.Write.Print("\t[+] Successfully requested api!\n", pystyle.Colors.green, interval=0)
    lock.release()

Expected behavior
In case you use a proxy, it should request the api as usual without any issue.

[lovelydinosaur]

It's not obvious to me how best to try to help with resolving this.

• Is this issue occurring consistently?
• Are you able to try with requests as an alternative? (To determine if this is a client-specific issue or not.)

[FuckingToasters]

It's not obvious to me how best to try to help with resolving this.

• Is this issue occurring consistently?
• Are you able to try with requests as an alternative? (To determine if this is a client-specific issue or not.)

It seems that the issue is caused by rotating proxies. When choosing sticky ones with 30 seconds - 1 minute stickiness the issue don't happen that often. However it still would be nice to be able to use rotating proxies.