login.php causes Router blackout

Hi – I run several instances of wordpress across several hosts. Currently if I attempt to access ../wp-admin or ../wp-login.php of my wordpress instances hosted at one of my servers my Router disconnects. My support ticket at that hosting company has expired – they have advised me to contact my ISP – from which I await a response. I CAN access the dashboard of these instances using a proxy. This issue is common across IE/MZFirefox/Safari/Chrome and Opera, all of which have been cleared of cookies/cache and checked – anybody have any ideas?