Stale WAN lease on RT-AC86U with 384.15

[rdy2]

Yesterday my internet appeared to be down. I looked at the router and had an assigned WAN address of 67.4.100.253. Pings to 8.8.8.8 and to the supposed to be gateway 67.4.100.254 failed. Odd enough, the log was reporting inbound DROP frames on my address. I power cycled modem(bridge mode) to no effect. I rebooted router from GUI a couple of times. I power cycled both, modem and router. Problem remained.
I let it seat overnight, hoping some network operation might fix it, but this morning the problem was still present.
I replaced the 86U with an older 68U on 384.3. It came up with no problems, but with an new assigned address 63.229.221.207. So somehow the 86U had failed to get a lease.
I chained the 86U to the 68U and it came up with a lease on the local network and no problems. I powered down both and reconnected the 86U to the modem. It came up with no problems, this time with new WAN address 76.4.97.31.


How can this be explained? I would have expected power recycle to renew lease. Is it that the firmware, on start up, asks the DHCP server to use the old address? Is there a way to force a release/renew if this happens again? Would an overnight power off fix it?

 

[ColinTaylor]

ISP issue. Ignore it unless it happens again.

 

[L&LD]

@rdy2 next time you may want to completely power down and unplug all network equipment (but at least the modem and router) with all power cables removed from both the wall (AC power jacks) and the equipment themselves (including all USB and Ethernet cables too). Leave everything power off for at least 10 minutes (and if that is insufficient, 20 minutes or next time 60 minutes or more) and then plug in the modem. Wait 5 minutes for it to fully boot up before connecting the Ethernet cable between it and the router and then power on the router.

This process will 'reset' the connection between your modem/router and your ISP in the shortest possible time.

If it really is an ISP issue, you will at least know sooner than overnight too.

HTH.

 

[davidangel64]

Change your mac address on your RT-AC86U to that of the RT-AC68U.

 

[rdy2]

@rdy2 next time you may want to completely power down and unplug all network equipment (but at least the modem and router) with all power cables removed from both the wall (AC power jacks) and the equipment themselves (including all USB and Ethernet cables too). Leave everything power off for at least 10 minutes (and if that is insufficient, 20 minutes or next time 60 minutes or more) and then plug in the modem. Wait 5 minutes for it to fully boot up before connecting the Ethernet cable between it and the router and then power on the router.

This process will 'reset' the connection between your modem/router and your ISP in the shortest possible time.

If it really is an ISP issue, you will at least know sooner than overnight too.

HTH.

You have a point in trying longer power off cycles. Time ago I installed two half-space power switches by the outlets, so I can recycle without messing with cables. Next time I will try a substantial time.

 

[rdy2]

Change your mac address on your RT-AC86U to that of the RT-AC68U.

Thank you, but that is not a workable solution. I may as well keep swapping router back and forth. I am not sure I made clear that the 86U has been working for months.

I was wondering if there is an easy way to force release/renew with a script. That might work. Next time I will try power off for 15 minutes.

 

[rdy2]

ISP issue. Ignore it unless it happens again.

Yes, it really looks like they have a problem with the lease updates. It looked I was connected, receiving frames, but my gateway was wrong, so I could not send outbound frames.

 

[ColinTaylor]

I was wondering if there is an easy way to force release/renew with a script.

If you reboot your router through the GUI the shutdown process will automatically send a release request to the ISP server. See here. The stop_wan function will issue a SIGUSR2 followed by a SIGTERM. You could do this manually in a script but you would just be duplicating what the router is already doing.

Yes, it really looks like they have a problem with the lease updates. It looked I was connected, receiving frames, but my gateway was wrong, so I could not send outbound frames.

This is the main problem. If the upstream DHCP server is not working properly then sending it a release request doesn't achieve anything.