m0n0wall Forum - issue with captive portal or dhcp server?

Ill start off saying i did not configure this monowall so Ill try to give you as much info as possible. Basicly heres the problem. Between 4:30pm to 7:00pm patrons have issues connecting to wireless. I know this because we have the librarians document the date and time of the issue. The patrons say their laptops say they are connected to wireless. But their browser doesnt load page we have set up with library rules, and button saying they agree. I belive this is called the captive portal. It takes about 3 reboots of monowall to get things going again. This happen to anyone else?