What region are you located?
What ISP Service do you have? Cable or DSL?
What ISP Modem do you have? Stand Alone or built in router?
What ISP Modem make and model do you have?
If this modem has a built in router, it's best to bridge the modem. Having 2 routers on the same line can cause connection problems.
To tell if the modem is bridged or not, look at the routers web page, Status/Device Info/Wan Section, if there is a 192.168.0.# address in the WAN IP address field, then the modem is not bridged.
Some things to try:
Turn off ALL QoS or Disable Traffic Shaping (DIR only) GameFuel (DGL only and if ON.) options. Advanced/QoS or Gamefuel.
Turn off Advanced DNS Services if you have this option under Setup/Internet/Manual.
Turn on DNS Relay under Setup/Networking.
Setup DHCP reserved IP addresses for all devices ON the router. Setup/Networking
Ensure devices are set to auto obtain an IP address.
Set Firewall settings to Endpoint Independent for TCP and UDP under Advanced/Firewall.
Enable uPnP and Multi-cast Streaming under Advanced/Networking.
What wireless modes are you using? Under Setup/Wireless/Manual.
Try single mode G or mixed G and N?
I might upgrade the B device is possible to a G or N wireless adapter.
Channel Width set for Auto 20/40Mhz or try 20Mhz only.
Try setting a manual channel to a open or unused channel.
What security mode are you using? Preferred security is WPA-Personal. WPA2/AES Only. Some WiFi adapters don't support AES, so you might want to try TPIK only or Auto.
Any cordless house phones?Any other WiFi routers in the area? Use InSSIDer to find out.
Turn off Short GI, WLAN Partition and Extra Wireless Protection if you have it. Under Advanced/Advanced Wireless.
If some of the suggestions don't seem to help, a FW update might be needed. However this depends on your external conditions. Having a lot of other WiFi routers near by will be a cause of signal loss on the router as the router has to stop and try to find a open channel. No FW update will fix this. If there are many WiFi routers on 2.4Ghz, it might be an option to get into the 5Ghz radio band in your area. Let us know.