I don't know much about root or custom ROMs, so unfortunately I can't help you that much from that perspective. It would still help if you gave more details about what problems you're having. Does your phone even see the wifi hotspot (i.e., does the hotspot show up in your wifi list)? Does it show up in the list, but just not want to connect? Some basic things to try, in case you haven't already:
1. Reboot the phone.
2. Reboot the router.
3. On the phone, forget the hotspot's settings, then re-connect and reenter the password.
4. Try changing the router's security (e.g., from WPA to WEP, or AES to TKIP, or vice-versa)
5. Try turning off the router's security temporarily
6. Try using a static IP address instead of dynamic.