PurpleAir sensors will only communicate with the following fully qualified domain (FQDN) hostnames:
http://www.purpleair.com
http://api.purpleair.com
update.purpleair.com
sensors-ingest.wunderground.com
pool.ntp.org
www.googleapis.com
Outgoing ports used by PurpleAir sensors:
HTTP: 80
HTTPS: 443
DNS: 53
NTP: 123
Learn More
Sensor WiFi and Registration
WiFi Troubleshooting
WiFi Status Indicators