It is because the other routers are trying to authenticate with the Telkom exchange as well. Everyone connected to the same exchange as you will try to authenticate at the same time. If you are not able to acquire any connection after a power outage, you may powercycle the router by unplugging and re-plugging the power cord. However, if the powercycle still does not resolve the problem, you may need to reconfigure the wireless settings of your router. Maybe even wait 15 minutes before you try to do a power cycle.