Why your VPN will not connect: step-by-step troubleshooting

"It will not connect" is the most common complaint about any VPN. There are only a handful of causes, and most you can find yourself. Work through the steps in order: they are sorted from most to least common.

#1. Is there internet without the VPN?

Turn the VPN off and open any website. If nothing loads, the problem is the network, not the VPN. In hotels, cafés and airports you first have to pass the Wi-Fi sign-in page (captive portal); open any plain http site to make it appear.

#2. Are the date and time right?

All modern protocols use TLS, and TLS checks certificate validity dates. If your device's clock is a day behind or set to another year, the handshake fails. Turn on automatic date, time and time zone.

#3. Is another VPN running?

Only one VPN can run on a device at a time. Close other VPN apps, antivirus "secure connection" features and game "boosters". On Android, check Settings → Network → VPN: no other VPN should be set to always-on.

#4. Try another server

A server may be overloaded or temporarily unavailable. Pick another country or the closest server by latency. The live state of every server is on the servers page and at status.colitu.com.

#5. The network blocks UDP or a specific protocol

Some networks (mobile carriers, corporate Wi-Fi) block UDP or recognise certain protocols. The sign: it fails on mobile data but works on home Wi-Fi, or the other way round.

Colitu tries the protocols one after another: Hysteria2 (UDP), VLESS Reality and Trojan (TCP), and Shadowsocks 2022. Wait 10–20 seconds: if the first protocol fails, the app moves to the next. If the app shows a protocol list, pick a TCP option manually.

#6. Antivirus or firewall

On Windows an antivirus may block the VPN core as an "unknown network program". Add the Colitu folder to its exclusions. Check the installer against the SHA-256 on our verification page to make sure the file is genuine.

#7. Battery saving (Android)

Makers such as Xiaomi, Huawei and Samsung close background apps. If the VPN connects and then drops after a few minutes: Settings → Apps → Colitu → Battery → Unrestricted; on Xiaomi also enable Autostart.

#8. Connected, but sites do not open

• Check whether the internet sees your new address with our What is my IP tool.
• Change server: a particular site may block data-centre addresses.
• On Windows, turn on TUN mode if a program ignores the system proxy.

#9. Update the app

Old versions may not know about new protocols and addresses. Colitu updates itself, but check the version under About.

#If nothing helped

Contact support from the app: it attaches diagnostic information (version, device, recent errors) without your browsing history. Mention which network you are on (mobile carrier or Wi-Fi); it speeds up finding the cause a lot.