Problems With Sonicwall and Multiple PPPoE Connections

Now there’s an attention grabbing headline if ever I saw one!

Just a quick reminder post in case I come across this again or it helps anyone else.

We did some work for a client recently to replace their firewall with a shiny new Sonicwall NSA 2600.

In the days following the replacement we were getting reports of connectivity problems.

Inbound connections to the remote desktop server were dropping out and a web application they use was suffering from time outs.

Even pings out to various servers on the internet were giving us results that showed something wasn’t quite right.


The only thing that had changed was the firewall so we put the old one back in and everything returned to normal.

This meant I spent a few hours going through each setting. We’d set the new firewall up exactly the same as the old one but there was clearly buy ativan online reviews something different between the two.

We initially narrowed it down to a problem with the PPPoE connections.

This particular setup had three WAN connections, two of which were PPPoE. The other connection didn’t have any problem at all. 

After liaising with Sonicwall support we got to the bottom of it.

There is a setting in the WAN connection that needs to be enabled that wasn’t available with the previous firewall.

“Allow duplicate MAC addresses”


There is ONE article on the Sonicwall knowledgebase that mentions this setting.

The scenario discussed in the article doesn’t fit our setup though.

We weren’t using load balancing, both connections had a different default gateway and traffic was flowing across both connections, just not very well.

However, changing the setting worked. Turning it back off caused the issue to reoccur.

It’s been fine now for almost a month, 

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Andy Parkes is Technical Director at Coventry based IT support company IBIT Solutions. Formerly, coordinator of AMITPRO and Microsoft Partner Area Lead for 2012-2013. He also isn't a fan of describing himself in the third person.

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