Adapter em0 link state changing down/up on 11.1

[Ernie Luzar]

Tim Daneliuk wrote:
> On 08/02/2017 01:04 PM, Ernie Luzar wrote:
>> Hello List;
>>
>> Running 11.1 and em0 is a Intel Pro/1000.
>> I keep getting these messages
>> Kernel: em0: Link state changed to Down
>> Kernel: em0: Link state changed to Up
>>
>> This happens 3 to 8 times during a 24 hour period.
>> em0 is connected to the public internet and this down/up cycle
>> disconnects all browser connections that are active.
>>
>> What can I do to fix this?
> 
> I seem to recall seeing this same problem on a 9.x or 10.x system.  In
> my case the fix was to replace a failed component.  For the life of
> me I cannot recall whether it was the NIC, the cable, or the switch.  As
> a first step, at least, I'd swap cables.  If that doesn't fix it, move
> it to a different switch port - or better still, a different switch
> entirely.
> 

For the archive record
I replaced the cable between the gateway server and the Time Warner 
cable modem and the down/up messages have not happened in the last 24 hours.