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FAQ

Last updated October 8, 2026

A profile won’t add

The app tells you what’s wrong. Common cases:

  • “The profile uses … Cosmos supports VLESS and Reality.” — the profile uses another protocol. Cosmos works only with VLESS + Reality: set the server up for it, or ask whoever set up the server for a VLESS + Reality profile.
  • “This isn’t a profile link. It starts with https://” or “The link isn’t encrypted (http://).” — the link must start with https://.
  • “Can’t reach the provider.” — no internet connection, a wrong link, or the server isn’t responding.
  • “The provider didn’t return a profile (error …).” — the server didn’t return a profile. Check the link and that the server is working.
  • “This link doesn’t lead to a profile in a format Cosmos understands.” — the server doesn’t return a sing-box configuration. How to set it up — in Server setup.

It won’t connect

  • On iPhone, iPad and Mac — allow adding the VPN configuration when the system asks.
  • On Windows and Linux — check that the service is running (below).
  • Check the profile’s expiry and traffic in the Profiles tab: if it has expired or the traffic has run out, the connection won’t work until they’re renewed on the server.
  • Refresh the profile with ↻ on its card.

Expired or out of traffic

Expiry and traffic are set by the server. Cosmos Client doesn’t sell access — you can renew where the server is set up. If the server reports its contacts, they’re in the Provider tab.

Windows and Linux: “Service not running”

On a computer, the connection is kept up by the cosmos-client-daemon service, installed together with the app. If it isn’t running, the tray says Service not running, and you can’t connect.

Linux — check and restart the service:

systemctl status cosmos-client-daemon
sudo systemctl restart cosmos-client-daemon
journalctl -u cosmos-client-daemon -n 50   # latest service log entries

Windows — open Services (services.msc), find cosmos-client-daemon and start it. Or, in PowerShell as administrator:

Restart-Service cosmos-client-daemon

Still not working — reinstall the app: the installer or package installs and starts the service again.

Linux: no tray icon

In GNOME, the tray icon is shown through the AppIndicator extension. It’s enabled in Ubuntu; in Fedora and Arch you may need to install (gnome-shell-extension-appindicator) and enable it. Without the icon, closing the window closes the app, but VPN keeps running in the service.

How to send the log to support

  1. In the Cosmos tab, turn on Keep log — it’s off by default and nothing is recorded.
  2. Reproduce the problem.
  3. Open Log, tap ⋯ and Copy log — send the text to support.

The log keeps entries from the last 15 minutes. Only the server is kept in addresses — the path and parameters of the profile link are removed from the log. Still, look through the text before sending it. When you’re done, turn the log off — the entries are erased.

How to erase everything

In the Cosmos tab — Reset client: profiles, configurations, service details, the log and settings are erased, and VPN turns off. On iPhone, iPad and Mac, the system will ask for VPN permission again on the next connection.

Does the app collect my data?

No. There’s no sign-up, analytics or advertising; profiles and settings are stored only on your device — more in the Privacy Policy.