I will say this about Networking Configuration issues. Unlike other aspects of computing, Networking Config is very unforgiving. If you don't have it pretty-much right on correct, it just doesn't work. Certainly, there are some trouble-shooting steps, but as far as architecting networks, even mildly-complex SOHO setups, you need to know what you are doing, which is knowing more than just enough to be dangerous to router configurations.
IOW, you need an over-view undertanding of what your networking devices can do, and what sort of configuration you want them in, you can't just really "fuzz out" the configuration through trial-and-error, the same way that you might learn how to use a software application.
I don't claim to know it all, when it comes to networks, I have quite a lot left to learn (well, there's ALWAYS MORE to learn), but I do the best that I know how. (Most SOHO routers aren't horribly complex, and I'm handy and familiar with features of DD-WRT, Tomato, and Advanced Tomato, my newest experimental firmware experience.)
Edit: I suggest, that in order to access the repeater's config menus, that you need to manually go into your network adapter properties, into IPv4 Properties, and set a manual static IP and subnet, in the same range as the repeater's IP address, first, before trying to access it.
Edit: Reason why is, most repeater-type configs, get their IP addresses for the device and devices wirelessly connected to the repeater, from the DHCP server that the repeater is connected to wirelessly as a client / bridge, and if it can't connect (wifi settings wrong, wrong password, wrong channel, etc.), then it can't pull an IP from DHCP, to hand out to the devices plugged into it. That's why you should set a static IP, on the repeater itself, and then on the client device used to access the repeater FOR CONFIGURATION PURPOSES. During actual practice, when the repeater link is up, and working properly, then client(s) should be able to be set to DHCP / Dynamic IP, and still pull an IP from the upstream DHCP server on the primary router, and communicate on that subnet.