SysOp VNC Remote Desktop
Help centre

Support

Setup instructions, answers to the problems people hit most often, and a direct line to the developer.

Email support Troubleshooting
Contact

Get in touch

SysOp is developed by one person, so replies come directly from the developer — usually within two to three business days.

E-mail

The fastest way to reach support, in English or Russian.

svsarts@gmail.com

Report a bug

Describe what you did, what you expected and what happened instead. The details listed below make a fix much faster.

Suggest a feature

Requests are read and genuinely shape the roadmap. Tell us which server software you use and what is missing from your workflow.

When reporting a problem, please include:

  • • Your Android version and device model
  • • The SysOp version (Settings → About)
  • • The VNC server software and version (for example TightVNC 2.8.85)
  • • The exact error message shown on screen
  • • Whether the same server works from a desktop VNC client

Never include your server password, and blank out any host name or IP address you would rather not share.

Setup

Connecting for the first time

SysOp is a client only. A VNC server has to be running on the computer you want to control.

  1. Install and start a VNC server

    On Windows, TightVNC Server is the best match — it enables the optional file-transfer features. TigerVNC, RealVNC and the built-in screen-sharing services on Linux and macOS work as standard RFB servers.

  2. Set a server password

    Configure the password in the server itself. SysOp only sends the password you give it; it cannot create or change one on the server.

  3. Find the computer's address

    On Windows run ipconfig, on Linux or macOS run ip addr or ifconfig. Use the local address of the network both devices share — typically something like 192.168.1.25.

  4. Open the port on the firewall

    Allow incoming TCP connections on the VNC port (5900 by default) for your private network. Most first-time failures are firewall rules.

  5. Add the connection in the app

    Tap +, then fill in a display name, the host address, the port and the password. Saving stores the password in the Android Keystore.

  6. Connect and control

    Tap the entry to open the session. Pinch to zoom, drag to pan, open the on-screen keyboard from the toolbar and use the file browser icon to transfer files when the server supports it.

Troubleshooting

Fixes for the usual suspects

"Connection refused" or the connection times out

Work through these in order:

  • Confirm the VNC server is actually running on the computer — its tray icon should be visible.
  • Check that the phone and the computer are on the same network. Mobile data cannot reach a home LAN address.
  • Verify the port. 5900 is standard; some servers use 5901 or a display-number offset.
  • Allow the port through the firewall (Windows Defender Firewall → Inbound rules).
  • Test from a desktop VNC viewer on the same network. If that fails too, the problem is on the server side.
Authentication fails although the password is right

VNC Authentication truncates passwords to eight characters — a longer password may be accepted by one tool and rejected by another. Try setting a password of eight characters or fewer on the server. Also check whether the server distinguishes between a full-control password and a view-only password, and whether it requires a security type SysOp does not offer (for example RealVNC's proprietary encryption modes, which are not part of the RFB standard).

The picture is slow or tears on a weak network

Enable the Tight encoding on the server — it compresses far better than Raw or Hextile and is what SysOp requests first. Lowering the desktop resolution, disabling wallpaper and visual effects, and staying on 5 GHz Wi-Fi all help noticeably.

File transfer is unavailable

File transfer is a TightVNC 2.x extension rather than a part of the RFB standard. SysOp checks the capabilities the server advertises during the handshake and turns the feature off when the server does not support it. Use TightVNC Server 2.x and make sure file transfer is enabled in its configuration.

Some keys or shortcuts don't reach the remote computer

Android reserves certain combinations for itself — anything using the Meta/Windows key, and Alt+Tab — so they never reach the app. Send those from the on-screen keyboard instead, which has a dedicated Ctrl+Alt+Del key. If a hardware keyboard is not recognised at all, set physical keyboard support to Always on in Settings.

The on-screen keyboard hides part of the desktop

Switch the layout in Settings. Docked mode slides the desktop up so nothing is covered; floating mode gives you a draggable window whose opacity, key size and width can all be tuned.

The session drops when the app goes to the background

Aggressive battery optimisation can suspend the network connection. Exclude SysOp from battery optimisation in Android Settings → Apps → SysOp → Battery → Unrestricted. Held modifier keys are always released when a session loses focus, so nothing stays stuck down on the remote machine.

Can I connect over the internet?

Technically yes, but do not forward port 5900 to the open internet: RFB traffic is unencrypted and its authentication is weak. Connect to your home network over a VPN such as WireGuard or Tailscale, or forward the port through an SSH tunnel and point SysOp at 127.0.0.1 on the tunnelled port.

Reference

Requirements and limitations

System requirements

  • Android 6.0 (Marshmallow) or newer
  • Phone or tablet, portrait or landscape
  • A network route to the VNC server (LAN, VPN or SSH tunnel)
  • Roughly 60 MB of free storage

Known limitations

  • • RFB has no built-in encryption — use a VPN or SSH on untrusted networks
  • • File transfer requires a TightVNC 2.x server
  • • Proprietary RealVNC security types are not supported
  • • The remote cursor is not drawn; your device pointer is used instead
  • • Audio is not part of the RFB protocol and is not forwarded
More about the app Privacy Policy