Python Speedtest. Py Failing to Connect to Internet When Run from Cron

I have the following code

#!/usr/bin/python3.8

import subprocess
import requests
import datetime
import urllib3
urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

print("=============================================================");
now = datetime.datetime.now()
print(now);

# speedtest --single --json
speedout = subprocess.run(['speedtest', '--single', '--json'], stdout=subprocess.PIPE).stdout.decode('utf-8');
print("speedtest output:"+speedout);

now = datetime.datetime.now()
print(now);
print("=============================================================");

When I run it manually, it generates the following log

=============================================================
2021-04-26 12:23:14.869085
speedtest output:{"download": 48332978.441761896, "upload": 21216098.81470209, "ping": 43.796, "server": {"url": "", "lat": "-17.7450", "lon": "-48.6250", "name": "Caldas Novas", "country": "Brazil", "cc": "BR", "sponsor": "Hot Caldas Internet", "id": "40200", "host": "hotcaldas.lampinc.com.br:8080", "d": 230.63111881620188, "latency": 43.796}, "timestamp": "2021-04-26T15:23:15.343030Z", "bytes_sent": 26738688, "bytes_received": 60631816, "share": null, "client": {"ip": "179.xxx.xxx.14", "lat": "-1xxx", "lon": "-4xxx", "isp": "Vivo", "isprating": "3.7", "rating": "0", "ispdlavg": "0", "ispulavg": "0", "loggedin": "0", "country": "BR"}}
2021-04-26 12:23:39.011183
=============================================================

But when I place it on crontab (under my account) to run hourly:

0 * * * *         /myscripts/monitors/speedtest.py >> /mylogs/speedtest.log 2>&1

it generates the following log

ERROR: Unable to connect to servers to test latency.
=============================================================
2021-04-26 13:00:01.687964
speedtest output:
2021-04-26 13:00:13.539705
=============================================================

Note how the error message happens before the first ========

What could be happening?

Update. I added flush=True to all prints. It worked once but is failing again. Now the error msg changed

=============================================================
2021-04-26 16:00:01.943727
ERROR: Unable to connect to servers to test latency.
speedtest output:
2021-04-26 16:00:03.616226
=============================================================