Ok, Log into your Router, then goto Tools > Time
At the bottom of the page, Click on Copy Your Computer's Time Settings
Then click on the Save Settings Button.
If this doesn't take, then there was a problem with your Firmware update. If it does take, then you'll next want to do the following......
Enable Time Server then in the NTP Server Used : field MANUALLY enter: time.nist.gov
Then next you would go to the Time Zone Setting and select your Time Zone. If your area does Daylight savings, then you need to set the Offset field.
Basically such as where I live, our state participates in Daylight saving and as such, it's spring ahead and fall back. The difference for us is one hour. So for me, I would select +1:00
Some areas here in the States don't participate in Daylight savings. As for other areas in the world, I have no idea what the differences may be for the offset.
For the USA,
DST Start = March, 2nd week, Sunday, 2:00am
DST END = November, 1st week, Sunday, 2:00am
After you have everything set, use the Save Settings button again.
IF Your Firmware Update Failed
Then make sure that everything is disconnected from your router except for the computer you are using. This includes disconnecting the network cable to your modem from your router. Then disable your AntiVirus program and close any other programs that may be running.
Once you have done all this, repeat the process you used earlier to upgrade your firmware.
Then once the upgrade is complete, unplug your router and let it sit a minute or so before plugging it back in just to make sure there are no traces left in memory.
Good Luck