If you just purchased the router, you can always take it back to the store and tell them it is defective. Get an exchange and stay with the older firmware until DLink fixes the issue.
I will say the following post from another member cleared up my router reboots. Mine has been up for approx 20 days without a reboot:
To help address disconnection issues with the DLink DIR-655, make these settings on the router:
Under Advanced --> QOS engine --> QOS engine setup:
Uncheck Dynamic Fragmentation
Under Advanced --> Advanced Wireless -->Advanced Wireless Settings:
Uncheck Short GI
Under Advanced --> Wi-Fi Protected Setup:
Uncheck enable
Under Advanced --> Secure Spot:
Uncheck Enable Securespot services
Under Setup --> Internet --> Manual Internet Connection Setup:
Uncheck Enable Advanced DNS Service
Under Setup --> Network Settings --> Router Settings:
Uncheck Enable DNS Relay
Under Setup --> Network Settings --> DHCP Server Settings:
Check Always Broadcast
Under Setup --> USB Settings:
Set "My USB type" to WCN Configuration
Under Setup --> Wireless Settings --> Manual Wireless Network Setup:
Set 802.11 Mode to Mixed n,g,b
Check Enable Auto Channel Scan
Set Transmission rate to Best (automatic)
Set channel width to Auto 20/40
security mode to WPA personal
Set Visibility Status to visible
Under Wireless Security Mode set:
Set Security mode WPA-Personal
Set WPA Mode to WPA2 Only
Cipher type AES
Pre-Shared Key is required