Checking this morning, I too had the a problem with my DIR-865L this morning, it's shows a red X and says my router is OFF Line. I just checked again on my iPhone and it's now accessible however checking from my work PC, the status says that it can't access the router.
I enabled the remote access to my router and rebooted. Now both iPhone and PC report as being OFFLINE again. I'll check back later.
I presume D-Link is working on it.