When it won't connect.
FL Connect links the two computers directly, so no video ever touches our servers. That is what keeps it fast and private. It also means your network has to let that direct connection through. When it doesn't, this is almost always why.
It is almost always a VPN.
FL Connect is peer to peer. Your computers find each other and talk directly. A lot of VPNs quietly block or reroute that kind of traffic, so the direct link never forms. You either can't connect at all, or you connect but never see any video.
If you or the person you are working with has a VPN running, start there. It is the single most common reason a session fails.
We keep video peer to peer on purpose. It holds latency down and keeps your audio off our servers, so there is no relay to fall back on. Switching the VPN off is the real fix, not a workaround.
Turn it off
Switch the VPN off completely, then reconnect. It is the quickest thing to try and it clears this up most of the time.
Or split-tunnel it
If you need the VPN running, add FL Connect to its split tunnelling list so its traffic skips the VPN.
Check both ends
One person on a P2P-blocking VPN is enough to break the link, so both of you should look, not just the host.
Firewall or strict NAT
FL Connect has to open a direct path between both machines. A tight firewall, a school or office network, or a router with strict NAT can block it. Allow FL Connect through Windows Firewall when it asks, and try a normal home network if you are on a managed one.
Run the connection test
Open Settings, Connection, Run test. It reads your NAT type and whether a direct path is possible. If it shows symmetric NAT or no candidates, your network or a VPN is the cause. Paste the result into Discord and we will read it with you.
Antivirus ate the installer
FL Connect is a small independent build and is not code signed yet, so some antivirus tools flag it just in case rather than for anything real. If the installer disappears or will not open, restore it from quarantine and allow it.
Black screen or frozen video
Usually a graphics driver or encoder hiccup. Update your GPU drivers and rejoin the session. If it sticks around, send the session log from Settings, Report a bug. It attaches everything we need on its own.