This is hopefully just a temporary issue but since it affects a lot of our users and may become more of an issue as time goes on it may be good to have info about it here.
This page is for you in case you have trouble with downloading files from the mod/map vault, your What's New tab doesn't load in the client, your flag isn't being shown in the IRC or if init lua files aren't being downloaded properly by the client.
The cause of these issues appears to be the fact that more and more Internet Service Providers use IPv6 instead of IPv4 in order to avoid running out of available IP addresses. Since FAF doesn't work with IPv6 properly (yet) we can only provide you with a workaround on your end.
In order to ensure that you use IPv4 you can simply disable IPv6 on your local network adapter.
Settings -> Network & Internet -> Change Adapter Options -> Right Click on your Adapter -> Properties