WAN Link rapidly switching between static and DHCP with one ISP

[Nash]

I recently upgraded an MX60 from 13.33 to 14.40. After the upgrade, their WAN link to their secondary ISP (Suddenlink) cannot maintain its static IP. It keeps reverting to pulling DHCP from that ISP in panic mode.

The primary WAN link is fine. I've upgraded several other 60s without seeing this kind of instability., with other ISPs.

ISP is telling us to upgrade to beta firmware, which isn't an option. If anything, we'll roll back.

Has anyone ever seen this before?

[BrechtSchamp]

It falls back to DHCP when it can't reach its gateway. But I suppose that can't be the reason here?

[NolanHerring]

I would bypass it for now and test it with a laptop with the STATIC IP information on the laptop, verify it works. If it doesn't, that would explain why its falling back to DHCP.

[Nash]

Unfortunately, it's four hours away, or else I'd absolutely have done the laptop thing. I'm also data gathering for my coworker who's technically managing this ticket, but keeps roping me in to act as the Meraki translator. 🙂

I'm checking to see if he's had someone on-site try with a laptop, to confirm that it's actually the MX. It's easy to latch onto testing with the device you can control when you're this far away...

I can tracert the problem GW successfully over WAN1, on another vendor, so I know it still exists. But it won't talk on WAN2. Hence, yeah, DHCP panic mode.

Thank you!

[PhilipDAth]

I can't find it now (it was in the release notes), but a while ago there was an ARP bug that affected a small number of ISPs.  Basically the MX would ARP for the configured default gateway and due to a bug this would fail, so it wouldn't use the configured settings on the WAN port.

This sounds very similar.  I would have thought it would be long fixed by 14.40.

[NolanHerring]

---

@PhilipDAth wrote:

I can't find it now (it was in the release notes), but a while ago there was an ARP bug that affected a small number of ISPs.  Basically the MX would ARP for the configured default gateway and due to a bug this would fail, so it wouldn't use the configured settings on the WAN port.

This sounds very similar.  I would have thought it would be long fixed by 14.40.

---

Oh snap really?

I have a single site (Spectrum ISP) that has that issue where the devices and MX will randomly show cloud connectivity loss. Not all at once mind you, just an AP here, or a switch there. So it makes the over-all ORG view 'green bar' look real bad.

Support said modem wasn't responding to ARPs so I assumed it was the modem from the ISP. They replaced. Still having the issue. Sort of just gave up on trying to fix it. 

Running 14.39

[Mloraditch]

I'm sorry to reply to such an old topic, we've had this issue in the past at a site, but we just got a customer who has new Optimum (formerly suddenlink) coax service in Texas and I'm seeing this issue. The optimum tech I talked to is definitely aware of something. He asked about my firmware version (18.107.10 on an MX100) The MX arps for the gateway and gets no response.

If @Nash ever became aware of a fix or anyone else who might read it, would love to hear. My Optimum ticket has been escalated to engineering.