i am running into the similar issues post 7.1.3 upgrade. Seems like Unraid becomes inaccessible from local network with fqdn and when i go through connect.unraid.net portal (access via IP) - i see 'Flash Drive corrupt' errors showing up in the UI. I had to shutdown the system. move the flash drive over to other USB port. start the system and its work fine for another day until error popped up again. I will have to look into the diag logs and post here as to what is happening - obviously flash drive and usb port seems to be working fine from it appears.