It sounds like you are connecting via a system like the one mentioned here: DSL Extreme - Opening multiple PPPoE sessions Support Article
I've worked with this type of connection before and it is like you said, each user signs on at the computer level via PPPoE. In the case of the people that I was helping in a similar situation, each person was assigned an internet facing (routable) IP address - meaning that the "modem/router/WiFi access point" combo did not perform NAT.
Let's see if I can correctly summarize what is going on here:
The laptop has a wireless and a wired network adapter.
Both work fine when you are at university.
(Hence your conclusion that the drivers
When you are at the Hostel and you connect to the internet, some pages (like Facebook) will not load. This happens with WiFi and hard wired.
You have tried connecting a hard wire (LAN cable) directly to the Hostel's modem. You let the modem make the PPPoE connection to the internet. When you connect to the Hostel's WiFi, you must use PPPoE at the computer level to get an IP address. In both cases (WiFi/wired), the data flowing to and from Facebook is via a PPPoe connection.
If you search the internet for... pppoe mtu "windows 7" "won't load"
...you will come up with lots of returns
(some from this forum)
Your connection to the internet while at university probably uses a "normal" MTU. PPPoE connections usually have a lower MTU to account for the 15% overhead for that type of connection.
The MTU should
automatically adjust on computers running Windows 7. The auto-adjust process depends somewhat on ICMP traffic - which is blocked by some web servers.
So - all of that to say this:
You might have a driver
problem with both network adapters (especially if they happen to be from the same vendor). Both network adapters might work fine as long as no MTU adjustments are needed. But both might crap out on a PPPoE connection.
You can hunt for the latest drivers or play with the MTU using this info: Change your MTU under Vista or Windows 7 richard-slater.co.uk
Of course, I could be wrong about all of this :-)