Gateway problem

i've encounter an problem of my d-link router DSL-500t,the default gateway will suddenly appear online,cause all others LAN com cant make access to internet.is there any solution to fix this problem,thanks.

Did you check with tech support at DLINK if there are any know issues with this device? Also when last did you update the firmware? Those are task I would consider first.

i didnt upgrade the firmware,before this happen,i've reset the router,then this problem just showed up.i've found the firmware for update,(ADSL2/2+ firmware for DSL-500T),isnt necessary to upgrade>?

Okay do this...

1. shutdown the other lan computers
2. Reset this router and turn it off
3. connect one LAN com to this router
4. turn on PC connected to this router and turn on router
5. connect to the router gui and see if it sees the PC connected to it.
6. Make sure all connections DHCP, DNS, Gateway, Subnet area all correct.
7. Ping this site and see if it's pingable..

i've done all those steps,seen all working fine.i'll monitoring it see whether the problem happen again.

after few days monitoring,the problem still coming back,i dont have any method to solve it,just switch the router off and on while the gateway ip offline.is there other solution>?

hum; I found DSL-500 but not the 500t; suggest you call or email D-Link support
re firmware update for your device. If at all possible, I would apply the update.

There's no reason for your router to present Gateway Offline to your LAN systems.
Just be sure it's not reporting the ISP gateway offline.

Here's the link for the 500 firmware.
BE CAUTIOUS