Syncing NTP Time On RT-N66U As Second Router

[MCDJ]

I have an Asus RT-AC3100 on which the 2.5GHz wifi band died. I also have an old Asus RT-N66U on which the 5GHz wifi band died. So, I decided to disable the 2.5GHz channel on the AC3100, disable the 5GHz channel on the N66U, and connect the N66U as a client to the AC3100, thereby extending the network. The N66U doesn't assign IPs; all are assigned by the AC3100. It works well so far.

My AC3100 has been acting up lately and I decided to create a JFFS script to reboot it nightly. That also works well. But the N66U has problems syncing the time through the AC3100. I read somewhere that the problem is that NTPD needs access to the WAN interface. So, what I did was, enable the NTPD server on the AC3100, and specify the NTP service on the N66U to sync the time against the NTDP server on the AC3100. Like so:

pool.ntp.org => WAN/AC3100 => ntpd <= N66U

On the N66U admin GUI, it works like a charm; the time gets synchronized. So I set up a JFFS script to run on a cron/cru job to reboot the router nightly one hour after the AC3100 reboots. That however, isn't working. The time isn't being synchronized until I go to the Admin > System panel on the N66U. I know by looking at the logs.

My guess is that there is some process that runs when the Admin > System panel is loaded, but I don't know what that is. I'd like to know to create another cron job to run that process after the system reboots, synchronizing the time.

Any ideas? Thank you!

 

[eibgrad]

I assume by "connect the N66U as a client to the AC3100", what you really mean is that you configured the N66U as a WAP (wireless AP), where the WAN is disabled (or at least not used), you disabled its DHCP server, assigned it a static IP in the same network as the AC3100, and connected it to the AC3100 LAN to LAN.

A common mistake in such a configuration is to fail to also define a default gateway (which should be the LAN ip of the AC3100) and DNS servers for the N66U. Normally, in a routed configuration, all these items are automatically configured over the WAN. But in a WAP configuration, YOU have to make sure all these same settings are configured on the LAN side of the WAP. If you don't, the WAP has no internet access, and so it can do things like update the time.

 

[ColinTaylor]

I assume by "connect the N66U as a client to the AC3100", what you really mean is that you configured the N66U as a WAP (wireless AP), where the WAN is disabled (or at least not used), you disabled its DHCP server, assigned it a static IP in the same network as the AC3100, and connected it to the AC3100 LAN to LAN.

This type of manual configuration should not be necessary as the Asus has its own "AP mode" which takes care of all of that and reassigns the WAN port as an additional LAN port.

A common mistake in such a configuration is to fail to also define a default gateway (which should be the LAN ip of the AC3100) and DNS servers for the N66U. Normally, in a routed configuration, all these items are automatically configured over the WAN. But in a WAP configuration, YOU have to make sure all these same settings are configured on the LAN side of the WAP. If you don't, the WAP has no internet access, and so it can do things like update the time.

This has been an issue in the past. IIRC it has been fixed in later firmware versions. He doesn't say what firmware he is using.

 

[MCDJ]

I assume by "connect the N66U as a client to the AC3100", what you really mean is that you configured the N66U as a WAP (wireless AP), where the WAN is disabled (or at least not used), you disabled its DHCP server, assigned it a static IP in the same network as the AC3100, and connected it to the AC3100 LAN to LAN.

A common mistake in such a configuration is to fail to also define a default gateway (which should be the LAN ip of the AC3100) and DNS servers for the N66U. Normally, in a routed configuration, all these items are automatically configured over the WAN. But in a WAP configuration, YOU have to make sure all these same settings are configured on the LAN side of the WAP. If you don't, the WAP has no internet access, and so it can do things like update the time.

Thank you for your response @eibgrad. You are correct, the N66U is configured as you have described. I did set the default gateway to the IP of the first router. I also set DNS servers on the N66U (OpenDNS). None of that seem to make a difference in the ability of the N66U to synchronize the time. Note that I have clients connected via 2.5GHz wifi to the N66U, as well as wired clients. All of them can access the internet and resolve and ping names (e.g. google.com). It's only the router that can't update the time. Also, if I ssh into the router and try to ping anything (hostname or IP) I get an error (no network access or some such). Ping also fails from the N66U's admin gui tools/ping window. But clients connected have no problem at all. As a matter of fact, I'm replying right now from a Windows client connected on the 2.5GHz band of the N66U.

 

[ColinTaylor]

@MCDJ Is your RT-N66U configured for Wireless router mode or Access Point(AP) mode at Administration > Operation Mode?

What firmware version are you using?

 

[MCDJ]

Router mode. Asuswrt-Merlin 380.70

 

[ColinTaylor]

Router mode. Asuswrt-Merlin 380.70

You should be using it in AP Mode.

If you still have issues with NTP I'd suggest using John's Fork as it has many bug fixes and still actively supports the N66U.

P.S. It's 2.4GHz not 2.5GHz.

 

[K-2SO]

Router mode. Asuswrt-Merlin 380.70

@ColinTaylor is correct, as always. Router Mode with DHCP off and LAN connection often results in no NTP sync. AP Mode will fix it.

 

[MCDJ]

@ColinTaylor Correct, it's 2.4GHz. And yes, @ColinTaylor & @K-2SO, switching the 2nd router to AP fixed the problem. Thank you!!!