Basically, they have one main internet line. Main Router is connected to Internet and Second Router is connected to Main Router. After this, each apartment gets a Ethernet line either through Main Router or Second Router. Some renters (students) use this ethernet straight on their computer; while some use routers. I like to use my personal router.
Few months earlier, I was connected to Main Router >via> Ethernet >via> Personal Router. My personal router worked fine. Now, I am on the secondary router. When I connect to Second Router >via> Ethernet >via> Personal Router, there is problem - My Personal Router cannot get any IP from Second Router. It says "Getting IP from DHCP" and it stuck there. When I do diagnosis on Windows 7, it says DNS Server not responding.

I changed my Personal Router's LAN IP
I changed from Personal Router's WAN from Dynamic IP to Static IP
I disabled Personal Router's DHCP.
Nothing works....I am tired of this. Need some advice
Second Router is TP-LINK 340G
Personal Router is CNET CBR-970
Please Please Please help