Randomly Not Passing Traffic

[SolarCzar]

So I'm new (6mths) to OPNsense.  I have my AT&T modem in passthru mode and using an N5105 2.00GHz device as my router (256Gb NVME, 16Gb RAM), with 22.7.10_2 as the most recent load.

Right after the upgrade to .10 my modem would randomly stop passing traffic.  I would reboot and everything was fine for another 1-2 weeks and then the same.  I set up a CRON job to reboot the router once a week, but it's still occurring (I just edited the CRON job for daily reboot, until I can solve this). I had some nice guys on Reddit suggest a number of troubleshooting ideas.  Unfortunately, they are not working.

I've set port speed on modem & router to 1000baseT full duplex.  I've attempted on the WAN interface to reject DHCP from 192.168.48.1 from my AT&T modem.  This prevented the 172.x.x.x DHCP request to my router and locked it up, so I removed it, assuming I'm putting it in the wrong place.  Another has suggested a firmware update to my N5105, but I am still researching where to pull that file.

I need some direction from OPNSense experts on what to look for on troubleshooting best practices.  Thanks

[chemlud]

The modem (which?) is in "pass thru" mode, but hands out private IPs in the 172.x.x.x range? Really? The setup is unclear to me.

And the diagnosis could be a little more elaborate than "stop passing traffic". No IP on WAN? No DHCP? Could you please provide more details? A BIOS update is never a bad thing (besides you can bork your hardware completely if you do something wrong), have a look at the homepage of the vendor for details...

[SolarCzar]

So through a chat on Reddit, a guy was having a similar issue and relayed this...

TheITMan19: Did you note the WAN IP address at 4am? Can you check this next time?

SolarCzar: Yeah, the normal 172.x.x.x was replaced with 0.0.0.0. On the Gateway widget where it would display the WAN_DHCP 172.x.x.1 was no longer present. Once I removed the 192.168.48.1 from the rejected DHCP field under the WAN interface, applied, and rebooted, it was up working fine. Don't know what any of this means exactly.

TheITMan19:When your modem is in pass through mode, it has the capability to hand out an IP Address but it’s the upstream router which hands out the IP address for your router (in my scenario). In this instance it shows that your upstream modem appears to be handing out DHCP which is used for your router. Sometimes when your lease expires and the router tries to obtain a new lease the upstream modem replies before the upstream router and the modem gives a lease when is no good hence blocking that DHCP server so to speak. You need to find someone who can direct you to the logs to navigate through when you experience the issues.


Does this help?

[chemlud]

Sorry, but in my experience a bridged modem (pass thru) hands out no IP, as long a the upstream DHCP server is available, i.e. the connection is up. You lose the IP on WAN and don't get a new lease, right? I would try rebooting the modem, not the sense and then try to obtain a fresh WAN IP (button close to DCHP on Interfaces -> Overview -> WAN).

Why would that happen? I have no idea. Is it a cable modem? Fiber? My WAN IP lease never expires in my experience with cable modem in bridged mode (or fiber converter).

[SolarCzar]

So as I dig deeper...

this is the settings on my AT&T Fiber modem for passthrough...DHCPS-fixed and pointed at the MAC address of my N5105 router with OPNSense, which would be correct.  The lease time is set for 10 minutes.  That sounds thin right?  I changed it to 1 day to try, but figured experts on OPNSense forum who read this can provide more insight...

[chemlud]

Never seen something like this, I'm out ;-) Why not set the lease time to 2 days and obtain a fresh IP (private?) every day (half of lease time).

Under System -> Log Files -> General you can filter for dhclient and see if you find something elucidating...

[SolarCzar]

Thanks for the try regardless....

[cookiemonster]

So as I dig deeper...

this is the settings on my AT&T Fiber modem for passthrough...DHCPS-fixed and pointed at the MAC address of my N5105 router with OPNSense, which would be correct.  The lease time is set for 10 minutes.  That sounds thin right?  I changed it to 1 day to try, but figured experts on OPNSense forum who read this can provide more insight...

I'm in a different country, so no AT&T knowledge but if these pages are applicable https://www.att.com/support/smallbusiness/article/smb-internet/KM1188700/ then it looks your latest setup appears right.