I'm using an Efika MX as a home router using the normal Ubuntu install media and the latest smarttop kernel. 99.9% of the time, it is fine. However, it has a tendency to randomly lose one of the network interfaces. The only kernel message is the watchdog timer timing out on the interface, and any attempt to ifdown the interface hangs forever.
The problem continues to occur in all combinations of Ethernet interfaces, from the original one-Ethernet-port-does-PPPoE-and-LAN setup to the current built-in + double USB Ethernet (one for PPPoE, one for LAN, one for a second uplink) setup, regardless of which cable is in which port. I have encountered this across three kernel versions, two separate Efika smarttops of different revisions, four complete OS reinstalls, three different root media. I have spent hundreds of hours spread over roughly a year fruitlessly trying to debug this problem. I've combed over everything: firewall rules, traffic control scripts... I've even tried clumsily poking the driver source without success.
Sometimes the problem occurs with no known cause, but some things reliably trigger it. When one user tries to log into her Yahoo! webmail account, around 75% of the time this results in a hang. Other users can get to theirs fine, but she's the only one who uses Windows. When anyone on the network tries to use OnLive, this works anywhere from less than a second to hours before a hang. (When OnLive causes the hang, ONLY the LAN interface ever hangs. The secondary uplink and PPPoE interfaces remain up, no matter which one OnLive was being routed over.) High-bandwidth tasks like large HTTP downloads, BitTorrent, and Steam always work perfectly, as well as most online games.
After disproving thousands of theories, the only one I have left is that an issue very similar to this one apparently affected FreeBSD on this chispet as referenced here. (This Efika's internal Ethernet uses the AX88772A chipset, and the two USB Ethernet adaptors use AX88772.) It is my thinking that something like it is affecting Linux's ASIX driver as well.
-:sigma.SB

It could easily be a driver problem. I have a USB-Ethernet adapter, which never worked well with the PPC EFIKA, so I gave up and used a PCI Ethernet card instead.

Then I used the same USB-Ethernet adapter for months without a single problem since last September with a Sheeva plug. That plug died two days ago, so I'll give EFIKA MX TO2 a try as a router once I have a little time to set it up.

_________________
CzP
http://czanik.blogs.balabit.com/

Well, no luck here. My Internet provider requires to use a fixed MAC address. The machine which had that MAC died 5+ years ago. With PCI Ethernet adapters when I do an then the card starts to work with the new MAC address.

When I do this with an USB based Ethernet adapter, ifconfig shows the MAC change, I get an IP address by DHCP, but no further traffic.

The EFIKA MX Ethernet port is USB based...

_________________
CzP
http://czanik.blogs.balabit.com/

OK. There is still some hope. Suddenly it started to work with the EFIKA MX built-in Ethernet adapter. Now I have to figure out how/why/etc. :-)

_________________
CzP
http://czanik.blogs.balabit.com/

And after updating my SmartTop to the latest firmware and latest kernel, setting the MAC address works quickly and reliably.
If you are in a similar situation (ISP doing MAC filtering), you can do a similar config in your /etc/network/interfaces file:
The important line here is the pre-up, which sets the MAC address to the one needed by the ISP. The next line just calls my firewall rules.

_________________
CzP
http://czanik.blogs.balabit.com/