(Pocket-lint) - VPNs are wonderful things, but inevitably you’re going to encounter a few issues with them from time to time: when you’re connecting to faraway servers it’s always possible that you’ll hit the odd online obstacle. The good news is that the majority of VPN problems are easy to identify and to solve. So let’s discover the most common ones and how to fix them. But before we do, let’s quickly recap on what a VPN actually does.

A VPN is a virtual private network, and it acts as a middleman between you and the site or service you’re using. Instead of your data travelling directly to that site or service it travels via the VPN’s servers, and those servers encrypt your data so it can’t be intercepted and disguise your location so the site doesn’t know where you are. You’ll often find that problems such as unavailable websites or sluggish performance aren’t the VPN but the site or service you’re using it to connect to.

1. The VPN is constantly dropping the connection

For persistent irritations such as frequently dropped connection, the problem could be interference. Is this the first VPN app you’ve installed, or are there multiple VPNs sitting in your Programs or Applications folder? Multiple VPNs can interfere with one another, and not in a good way. So rule one of VPN troubleshooting is to make sure you only have one VPN to troubleshoot. If you’re running Firewall software, see if that’s getting in the way of your connection too; if the problem is on a mobile, try disabling its battery-saving features.

2. The VPN server isn’t responding

Servers can and do fail or become unresponsive from time to time. They could be overloaded, they could be suffering from local network congestion or they might have been added to a site blocklist. If your VPN enables you to switch servers, either by specific location or by country (paid-for ones usually do), do that. If it doesn’t work at first, try a location that’s nowhere near the original one.

3. The site or service isn’t working

Did it work with your VPN switched off? Sometimes the simplest explanation is the likeliest and the site you’re trying to access may be down. But if it isn’t and you’re not getting any joy with the VPN enabled, try checking the following:

See if the site is blocking your VPN provider 

Some sites block known VPN services, so for example Netflix is famously not keen on VPN users bypassing its geographical restrictions and some VPN apps simply don’t work with it. It’s worth asking Google whether there are any known issues between the site you’re trying to access and the VPN you’re trying to access it with.

Update the VPN app

Yes, this is similar to “have you switched it off and back on again?”, which we’re sure you’ve already done. But many irritations are known to the VPN services and fixed in their latest releases, so it’s important to make sure you have the most up-to-date client app.

Change the protocol

Most VPN apps have an “automatic” setting that chooses the right protocol (networking language) for the site or service you’re using. But automatic settings aren’t always foolproof, and you can often magically make your VPN work by changing to OpenVPN or another protocol instead. Your VPN’s help pages will tell you how to do this and if there are any security implications, so for example the L2TP/IPSec protocol is fairly weak compared to others.

4. The connection is really, really slow

Assuming your VPN is a paid-for service – free ones often prioritise their paid members and typically don’t support streaming – then the culprit may be network congestion, either between you and the VPN server or between the VPN server and the site or service you’re accessing. The potential fix for both is to change to a different server. If that doesn’t work, try a different protocol.

5. You can’t send email when the VPN is on

Are they okay with browser-based email? Then chances are the problem is port 25. Some VPN clients block TCP port 25, which is used by some email apps and services for outgoing email. Check your VPN provider’s online support to find out which ports they don’t block and configure your email app accordingly.

Writing by Carrie Marshall. Editing by Dan Grabham.