Maximum PC

I'm renting a room in a house with a wireless network. I've been able to connect my numerous devices (2 phones, laptop, & tablet) in the past with no issue, but the signal has been weak. Therefore, I went out and got a wireless extender (Cisco RE1000). I set it up with no problems, and used it for a day or two to great success. However, starting last Friday, none of my devices could (and still can't) connect to the network. I unplugged the wireless extender, I removed the wireless network profile from my devices - I just can't connect. A few of my devices can't even see the network anymore. The owner has reset the router (unplugged, then plugged back in) a couple times.

During this time, the owners have had zero problems connecting, whether it's their Wii or laptops or whatever else they have. I'm going to request access to the router to see if I can fix this issue, but I don't want to adversely affect their connections.

I've set up and maintained a wireless network in my own apartment and home, so I'm not completely stupid - just mildly so. I think their network was set up by their ISP. My theory is that this could be a DHCP lease issue, but I'm not an expert. What are my next steps?

Thanks for the help in advance.