Folks, I needs some help here, please. We have a Balance 20 (HW3, FW 7.0.2) at a remote communications site which is fed by Time-Warner/Spectrum cable (WAN 1), Sprint 4G (via wi-fi adapter, WAN 2), and AT&T 4G (set as cold standby on WAN 3 - USB). Once in a while WAN 1 fails. (Always at the worst time, of course.) As I write this it shows “connecting” – but never does. So, as I write this, WAN 1 is down – still “connecting.”
Here’s what I’ve done to troubleshoot:
Connected a laptop directly to the Motorola SB6141 cable modem. A 1GB link was established and connectivity was as expected.
Rebooted the cable modem (several times) – no effect.
Rebooted the B20 – no effect.
Changed the WAN 1 port setting from “Auto” to 1Gb, full duplex, with “advertise speed” checked [going back through the forum this seemed to fix some situations for others] – no effect.
Changed ethernet cables – no effect.
Swapped WAN 1 and 2 (changed Spring 4G to WAN 1 and T-W to WAN 2 – Sprint 4G worked fine on the WAN 1 port.
So, where’s what I think I learned:
All cables are OK.
I had originally suspected a bad port on the B20 - not true as the other WAN worked fine there.
The modem is OK as it worked fine with a computer connected directly to it.
The frequently-recommended “solution” of locking the B20 port to 1 Gb did not resolve the issue.
At this point I’m out of ideas. I’ll appreciate some help.
Added: I just took one more step to troubleshoot: Going back through the forum I found where it was suggested to insert an unmanaged switch between modem and router. I did. Presto! Connectivity!
While this is a great troubleshooting step, and is OK on a temporary basis, we certainly don’t want to leave it that way! (Kludges are not welcome here.) Obvious question: “What changed?” – and the answer is “nothing!”
So, how should this issue be addressed in the longer term?
Hello @Rick-DC,
What is the Port Speed & MTU size you have the WAN connection set to? Ask the provider/carrier for what they expect it to be for the connection to the modem/bridge.
We have been caught out previously with a combined Port Speed & MTU mismatch once that was causing a similar situation to what you have written, once we set the setting up manually as supplied from the carrier/provider the issues went away, the connection has not missed a beat since.
Happy to Help,
Marcus
Great thought, Marcus – as always. I’ll do that. The MTU is what I have my eye on. The modem has a 1Gb interface. and has been OK.
But if that’s’ the issue, I’m wondering why this problem only occurs about once every few months. I have to ask myself: “What happened at 0230 this morning to cause the problem?” Strange.
I’ve been unable to find anything as to what the “preferred” MTU setting should be. But I found when I changed it to “Auto” after which I interpret to be a “negotiation session” the B20 once again connected to the Motorola modem.
I’m still mystified as to what caused the loss of connection between B20 and modem.
Hello @Rick-DC,
I know that you already know of this though if the Balance 20 does it again, download the diagnostic report from the router and raise a support ticket with the report attached, the team at Peplink may be able to see something within the report that could isolate the issue.
Happy to Help,
Marcus
Yes, you are right, of course. I had hoped not to bother the folks at “Peplink HQ” but that will certainly be the next step.
I always appreciate your advice – TU!
Hi TK. Yes, I saw that and tried it but was not successful. Right now the B20 is set at 1Gb, advertise speed and to negotiate MTU. These are not settings I would normally use but it seems to have worked – at least for now.
What is bothersome about this is that the previous setting (Auto, advertise and MTU of 1492) worked for several months – then failed.
Thanks for the pointer to that thread – all help is always appreciated!
