Problem to connect to D-Link DIR-655

I have MacBook Pro with Lion 7.1 and a router D-link DIR 655 (with latest firmware). I have had problem with the WiFi connection now and then. Just now I can not see my router in list but I can see many neigbours. It happends that I can see the router but then I connect I got timeout, I have iMac also with Lion which is connected to the same router with no problem. I have alse a IPad connected with no problem. I can connect to my wireless mobilmodem with help of a Dovado 3GN Router (WiFi connection). So what I can see I can connect things to the D-Link router but not the MacBookPro and I can connect the MacBook Pro to WiFi but not to D-Link DIR 655. What shall I do?