3.9.9: python built-in SSL module unable to connect to an IIS server (104 Connection reset by peer), but pyopenssl works fine

GitHub fields:

assignee = 'https://github.com/tiran'
closed_at = None
created_at = <Date 2021-12-22.19:02:14.295>
labels = ['expert-SSL', 'type-bug', '3.9']
title = '3.9.9: python built-in SSL module unable to connect to an IIS server (104 Connection reset by peer), but pyopenssl works fine'
updated_at = <Date 2021-12-24.11:47:37.482>
user = 'https://bugs.python.org/lkraav'

bugs.python.org fields:

activity = <Date 2021-12-24.11:47:37.482>
actor = 'lkraav'
assignee = 'christian.heimes'
closed = False
closed_date = None
closer = None
components = ['SSL']
creation = <Date 2021-12-22.19:02:14.295>
creator = 'lkraav'
dependencies = []
files = []
hgrepos = []
issue_num = 46156
keywords = []
message_count = 3.0
messages = ['409050', '409052', '409140']
nosy_count = 2.0
nosy_names = ['christian.heimes', 'lkraav']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue46156'
versions = ['Python 3.9']