Intermittent connectivity loss with em(4)

Morgan Wesström freebsd-database at
Fri Oct 11 08:20:31 UTC 2019

> It the host with the problem has an Intel Atom mainboard then the BIOS
> might be set to power off the NIC chip if there is no traffic on the
> port for an extended period.  The hub might be generating enough
> heartbeat traffic to keep the timeout from happening while the cable
> modem does not.
> We had this happen with some of our gateways built on Atom board
> systems. The BIOS was factory set to use this feature as a
> power-saving device on laptops.

I've scrutinized every BIOS setting as well as every jumper on the 
motherboard itself without finding anything power related with the 
exception of ACPI version. The fact that the link and activity LEDs 
remain on when connectivity is lost probably points to something else.

I went with Sergio's suggestion and put a small switch between my two 
routers and the cable modem and the problem went away. 10 hours running 
now with no loss of connectivity on either machine.

The behaviour intrigues me and I'd sure like to figure out why this 
happens but for now I will add SagemCom to my long list of manufacturers 
with buggy firmware/hardware. Unfortunately I have no freedom to chose 
another cable modem with my current ISP so I'll have to work around the 
problem for now.

Thank you all for your valuable input and support. :)


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