Hello All,
I may have found the area that causes the spontaneous reboot of routers when using the 1.7.x firmware.
I am currently using:
Gargoyle Version:1.7.X (Built 20150527-1912 git@7d816bd) - (I have also tried it with 1.7 and 1.7.1)
Model:D-Link DIR-835 rev. A1
Note: I was using the very same hardware and configuration manually configured with the older firmware 1.6.2 and it was running without any reboots for over 6 months.
Symptom:
Whenever I perform a speed test, the router would reboot. I have used 
http://www.speedtest.net and 
http://speedcheck.rogers.com/en.html
Usually the router would reboot almost everytime, occasionally it would not and you would have to do the speedtest back to back.
How to reproduce:
1) Configure your router with Quotas as shown by my examples below.
2) Ensure that they are all enabled.
3)  Perform a speed test from one of the above sites.
Where I believe the root cause for this issue is in the "Firewall" - "Quotas" section.
My configuration that confirm this:
All	Always	9GB/NA/NA			
Max Total Up+Down: Limit to 9.5 GBytes
Quota Resets: Everyday
Reset Hour: 12.00 am
Quota Is Active: Always   
When Exceeded: Throttle Bandwidth
Upload Limit:   64 kBytes
Download Limit:   512 kBytes
192.168.1.66	Always	1024MB/NA/NA	
Max Total Up+Down: Limit to 1024 MBytes
Quota Resets: Everyday
Reset Hour: 12.00 am
Quota Is Active: Always   
When Exceeded: Throttle Bandwidth
Upload Limit:   16 kBytes
Download Limit:   64 kBytes		
192.168.1.67	Always	1024MB/NA/NA
Max Total Up+Down: Limit to 1024 MBytes
Quota Resets: Everyday
Reset Hour: 12.00 am
Quota Is Active: Always   
When Exceeded: Throttle Bandwidth
Upload Limit:   16 kBytes
Download Limit:   64 kBytes		
	
192.168.1.68	Always	1024MB/NA/NA
Max Total Up+Down: Limit to 1024 MBytes
Quota Resets: Everyday
Reset Hour: 12.00 am
Quota Is Active: Always   
When Exceeded: Throttle Bandwidth
Upload Limit:   16 kBytes
Download Limit:   64 kBytes