This article is for IT or network administrators in charge of managing an organization’s network. If you ever need a hand with troubleshooting connection issues, we're here to help.
Older versions of the Slack desktop app can result in connection issues and even broken features.
Be sure the desktop app is up-to-date. If you have Slack deployed on multiple Windows machines across your org, you can have the app automatically update via MSI installer.
Slack must have a persistent connection between our messaging server and members’ apps or browsers. To do so, Slack uses WebSockets over port 443.
Proxies and firewalls can sometimes interrupt this connection. If someone using Slack can’t connect from a specific location, or if there’s a WebSocket failure in our Slack connection test, you’ll need to adjust your proxy or firewall to keep the connection to Slack open. Here’s how:
Visit https://my.slack.com/help/urls and add all specified URLs to your allowlist. If your environment requires access to multiple workspaces and/or orgs, visit that page from each workspace and/or org.
Check if your proxy is running SSL decryption. If it is, the proxy must either support WebSockets, or you’ll need to exempt the following domains: wss-primary.slack.com wss-backup.slack.com wss-mobile.slack.com
Network administrators can restrict access to specific Slack workspaces using proxy header injection on their network. The header injection solution has the same network requirements as above.
Network environment
Certain software, security settings, and firewalls can interfere with Slack connections:
