UDP vs TCP: what's best for your VPN speeds? | TechRadar
UDP vs TCP: what's best for your VPN speeds?
"Most VPNs are frustratingly vague about potential UDP issues. They might tell you that switching to UDP 'could affect reliability', for instance, but that's about it.
There's a good reason for this, though: there are so many variables involved that it's impossible to be more specific. You might see different results depending on your distance from a server, for instance. Or the server load. Or the routing to the server. Or the network quality, or the network load. There's no definitive answer here - it'll be different for everybody.
UDP problems you might see include more difficulty connecting to VPN servers, or noticeably reduced speeds when you are connected. These might happen only rarely, though, and as they can be caused by many other factors, you shouldn't immediately assume UDP is the problem.
The best approach is just to try it and see. If there's a speed boost, great. If you see new problems, just switch back to TCP and carry on as normal."