Windows Defender Firewall
On first start, Windows asks whether Tact-VC may use the network. Allow it on private and public networks.
Tact-VC checks the firewall at every start. If Settings → Help → System permissions shows the firewall as Blocked, the rules don't cover the network type you're on (Public, Private or Domain). To fix this:
- Open Windows Security → Firewall & network protection → Allow an app through firewall.
- Click Change settings.
- Find Tact-VC and tick both Private and Public.
- Click OK and restart Tact-VC.
Security programs
Antivirus and security suites with their own firewall: allow Tact-VC in their settings.
Check it worked
Settings → Help → System permissions shows the firewall as Allowed, and Check my network passes Replies.