Using a Virtual Private Network on public WiFi is a sensible security precaution, so what do you do when the network operator blocks VPNs?

We're told time and again that you need to play it safe when you're using someone else's Ethernet or WiFi if you can't personally vouch for the network's security – whether in a cafe, airport lounge or hotel room. The safest option is to engage a VPN to create an encrypted tunnel to the internet, ensuring that anyone else on that network can't eavesdrop on your online activities.

The problem is that some network operators deliberately block VPNs, out of concern that you might be up to no good. It's not just a problem when you travel to countries which want to rule the internet with an iron fist, you might even run into a VPN block in Australia at your local library.

Be prepared

If you put your privacy and online safety before a network operator's sense of paranoia then it pays to have a few VPN options in your bag of tricks. This includes signing up with VPN providers which support a range of protocols and have servers spread around the world.

Common VPN protocols include PPTP, L2TP/IPSEC, SSTP, IKEv2 and OpenVPN – they read like an alphabet soup but generally that's the order in which they're ranked in terms of security. You shouldn't put too much faith in PPTP these days, it's useful for masking your location to beat geo-blocking but it's not considered all that secure.

When you're more concerned about security than geo-dodging you should use a strong protocol and connect to the closest VPN server to your current location, in order to enjoy the best download speeds. That's why travellers should look for VPN providers with servers around the world.

Things are complicated by the fact that not every VPN server supports every VPN protocol, so you might not always be able to use the nearest server if you're determined to use a particular protocol.

VPN providers tend to publish a list of server addresses and support protocols around the globe, so it pays to do your research before you leave home and set up a few VPN options on all your devices.

Fly under the radar

If you're concerned about efforts to block VPN connections then you should look for VPN providers which support SSTP (Secure Socket Tunneling Protocol). The benefit of SSTP is that it basically disguises itself as ordinary web traffic, using the same ports, making it very difficult for network operators to block without blocking all internet access. \

One downside of SSTP is that it can be slower than other VPN protocols – it can save the day if you're struggling with limited internet access in some countries, although you might need to jump between servers in different countries in search of the best performance. It's also supported by fewer devices, although it is built into Windows 10.

You'll also find that SSTP is supported by fewer VPN providers, so you might need to shop around. Speed issues can be exacerbated by the fact that your VPN provider might only support SSTP on a handful of its servers, forcing you to rely on a server far away.

Some VPN providers like WiTopia tend to be deliberately vague when discussing their advanced options. WiTopia doesn't support SSTP but it does have 4D and 5D "stealth" modes buried deep in the advanced settings of its Windows and Mac apps. These basically work the same way as SSTP, although you'll need to contact WiTopia tech support in order to set them up.

Your mileage may vary when it comes to VPN blocking and it's worth trying other protocols first to see if you get lucky, but it's handy to have SSTP at your disposal as a last resort. Do you use a VPN on the road? What do you find is the best tool for the job?