WLAN Connectivity Problem

Problem:
Disconnection happens uncountable times a day on all workstation except mine

Solution:
1. Firewall setting on Workstation and router
2. Mac Filter
3. IP-Mac mapping
4. IP range limitation
5. WEP key
- The above methods are used to prevent unwanted outsider to build connection

Current IP assign method:
DHCP & IP-Mac Mapping

After turnning off DHCP:
Disconnection still happens
When discconection occurs, clients cannot connect back to Router