Time Machine

I have a NAS to use as a Time Machine drive for my MB Air and Mac Pro. Every month Time Machine does a verification of the sparse bundle for each machine. Unfortunately my NAS gets dropped on my WiFi network so Time Machine needs to create a new backup from scratch which takes a long time. The issue is that as Time Machine cannot detect my NAS it cannot verify the backup. Is there a way to force Time Machine to do another verify because by then I have got my NAS detected on my WiFi network?

My Mac Pro doesn't have this problem as it's connected to the router with a CAT5 cable.
Thanks

Alan