MacBookAir 11" - WiFi not connecting in Europe
Given you are using 2.4 GHz Wifi, there are 2 channels (namely 12 and 13) available in Europe, that are not allowed in the US and are therefore not supported by US-bought WIFI adapters. See Wi-Fi Channel availability

As far as I know Apple uses different Wifi-modules for european and US-models, so there's little hope to fix that in software.

Ask a fellow student to look up on which channel he is connected. If it's 12 or 13 you won't be able to connect.