I came across this thread on google and have to post my findings - the FW version in use is 384.10 and parental controls have been broken like this for years (I tried to use it on my N66U) but there seems to be little fuss about it...
Today I tried to put rules in to allow access to the internet from 8am to 12am. It seemed fine for an hour or 2 until my internet cut off at approx 6pm... weird. It was as if the rule had triggered early (and the UI said my machine was blocked).
I double checked the system time and all seemed fine. I SSH'd onto the router and the system time on there was fine as well. I tried to reboot the router and still the internet was off...
I started playing around with the parental controls menu until I produced this:
https://i.imgur.com/tDJg3C7.png
My internet was still blocked even though it was just after 7pm. The image you see there is the minimum number of boxes that I could leave blank or else the internet would start working again.
As time ticked over to 8pm my connection sprung back to life... so I decided to try checking the next box, as you can see here:
https://i.imgur.com/I421zSs.png
Low and behold I lost my access again. Now, bear in mind I'm an hour ahead because of summer time, and the fact that I had just rebooted the router this seems quite fishy... it's as if the parental controls are somehow measuring "time since reboot" as being 00:00
I checked iptables and the times in there match what's on the UI:
-A PCREDIRECT -s 192.168.1.253/32 -i br0 -m time --weekdays Sun --kerneltz -j ACCEPT
-A PCREDIRECT -s 192.168.1.253/32 -i br0 -m time --weekdays Mon,Tue,Wed --kerneltz -j ACCEPT
-A PCREDIRECT -s 192.168.1.253/32 -i br0 -m time --timestart 03:00:00 --timestop 23:59:59 --weekdays Thu --kerneltz -j ACCEPT
-A PCREDIRECT -s 192.168.1.253/32 -i br0 -m time --timestart 01:00:00 --timestop 23:59:59 --weekdays Fri --kerneltz -j ACCEPT
-A PCREDIRECT -s 192.168.1.253/32 -i br0 -m time --weekdays Sat --kerneltz -j ACCEPT
So this issue points to whatever component is making the decision to drop the packets time being out of sync? That's where my knowledge ends...
The network services filter on the firewall also seems to suffer from a similar issue, except it decides it will let some traffic through and some not, leading to half loaded / hanging pages. Is there any other way to reliably stop traffic at certain times? Bandwidth limiter only lets you set a minimum throughput of 0.1mbps....
The whole thing is woeful. How are there so few threads on this considering I know this hasn't worked for years now. Any input / pointing in the right direction would be helpful. I need ONE way to work because I'm setting it up for a friend