Python selenium proxy ERR_CONNECTION_RESET

I try to use a proxy server with selenium, on average I manage to properly connect and open the page once every few minutes. When I fail, an error pops up "net::ERR_CONNECTION_RESET" My code:

import undetected_chromedriver as webdriver
...
class ProxyExtension:
manifest_json = """
{
    "version": "1.0.0",
    "manifest_version": 2,
    "name": "Chrome Proxy",
    "permissions": [
        "proxy",
        "tabs",
        "unlimitedStorage",
        "storage",
        "<all_urls>",
        "webRequest",
        "webRequestBlocking"
    ],
    "background": {"scripts": ["background.js"]},
    "minimum_chrome_version": "76.0.0"
}
"""

background_js = """
var config = {
    mode: "fixed_servers",
    rules: {
        singleProxy: {
            scheme: "http",
            host: "%s",
            port: %d
        },
        bypassList: ["localhost"]
    }
};

chrome.proxy.settings.set({value: config, scope: "regular"}, function() {});

function callbackFn(details) {
    return {
        authCredentials: {
            username: "%s",
            password: "%s"
        }
    };
}

chrome.webRequest.onAuthRequired.addListener(
    callbackFn,
    { urls: ["<all_urls>"] },
    ['blocking']
);
"""

def __init__(self, host, port, user, password):
    self._dir = os.path.normpath(tempfile.mkdtemp())

    manifest_file = os.path.join(self._dir, "manifest.json")
    with open(manifest_file, mode="w") as f:
        f.write(self.manifest_json)

    background_js = self.background_js % (host, port, user, password)
    background_file = os.path.join(self._dir, "background.js")
    with open(background_file, mode="w") as f:
        f.write(background_js)

@property
def directory(self):
    return self._dir

def __del__(self):
    shutil.rmtree(self._dir)
options = [("123.123.123", 123, "xxx", "xxx"),
        ("", , "", ""),
        (),
        (),
        (),
        ()]


if __name__ == "__main__":
number_of_proxy = int(input('Input number of proxy: '))

proxy = options[number_of_proxy-1]
print(f'Bot start with proxy: {proxy}')
proxy_extension = ProxyExtension(*proxy)

options = webdriver.ChromeOptions()
options.add_argument(f"--load-extension={proxy_extension.directory}")
options.add_argument('--start-maximized') 
options.add_argument('--disable-dev-shm-usage')
driver = webdriver.Chrome(options=options)

driver.get(URL_CONF)

Could it be the fault of the proxy provider? I found some free proxies on the internet with which I have no such problem