import pandas as pd
import re


def extract_url(s):
    match = re.search(r'https?://([A-Za-z0-9._]+)', s)
    return match.group(1) if match else None


df = pd.DataFrame({
    'Stats_Access_Link': [
        'http://xcd32112.smart_meter.com',
        'https://example.com',
        'http://test_website.com',
        'https://another_example.com'
    ]
})

df['Stats_Access_Link'] = df['Stats_Access_Link'].apply(extract_url)

print(df['Stats_Access_Link'])