Losing Internet Connection

[nelsencd]

I have an SG-1100 that is randomly losing Internet. The ISP says that the link is flapping and that it is the SG-1100. Here are the logs:

Jul 12 15:25:44 check_reload_status 402 Reloading filter
Jul 12 15:25:44 php-fpm 14067 /rc.newwanip: rc.newwanip: on (IP address: x.x.x.x) (interface: WAN[wan]) (real interface: mvneta0.4090).
Jul 12 15:25:44 php-fpm 14067 /rc.newwanip: rc.newwanip: Info: starting on mvneta0.4090.
Jul 12 15:25:43 check_reload_status 402 Reloading filter
Jul 12 15:25:43 check_reload_status 402 rc.newwanip starting mvneta0.4090
Jul 12 15:25:43 php-fpm 14067 /rc.linkup: Hotplug event detected for WAN(wan) static IP (x.x.x.x )
Jul 12 15:25:42 kernel e6000sw0port3: link state changed to UP
Jul 12 15:25:42 check_reload_status 402 Linkup starting $e6000sw0port3
Jul 12 15:25:37 php-fpm 14067 /rc.newwanip: rc.newwanip: on (IP address: x.x.x.x) (interface: WAN[wan]) (real interface: mvneta0.4090).
Jul 12 15:25:37 php-fpm 14067 /rc.newwanip: rc.newwanip: Info: starting on mvneta0.4090.
Jul 12 15:25:37 php-fpm 14067 /rc.linkup: Hotplug event detected for WAN(wan) static IP (x.x.x.x )
Jul 12 15:25:36 check_reload_status 402 Reloading filter
Jul 12 15:25:36 check_reload_status 402 rc.newwanip starting mvneta0.4090
Jul 12 15:25:36 php-fpm 14067 /rc.linkup: Hotplug event detected for WAN(wan) static IP (x.x.x.x )
Jul 12 15:25:36 check_reload_status 402 Linkup starting $e6000sw0port3
Jul 12 15:25:36 kernel e6000sw0port3: link state changed to DOWN
Jul 12 15:25:35 check_reload_status 402 Linkup starting $e6000sw0port3

The connection will be stable for a while, and then this will happen again.

[Gertjan]

Jul 12 15:25:36 kernel e6000sw0port3: link state changed to DOWN

and a couple of seconds later :

Jul 12 15:25:42 kernel e6000sw0port3: link state changed to UP

The cable connection - probably physical or electrical, was lost.
Involved are :
The NICs on both sides (the data to electrical signal part). Swap interfaces so you can isolate the NIC that has problems.
The cable (plugs, wirte) Swap the cable..

[nelsencd]

I swapped cables, swapped the firewall for a white box pfSense, swapped the firewall with a UniFi USG, placed a switch in between the firewall and the ISP, and the interface was still flapping. The ISP is a WISP. They supposedly swapped out the radio on top of the roof, but it was still flapping. I wanted them to replace the cable and the PoE injector, but they didn't. We ended up hard setting the speed/duplex to 100 FDX and the connection is better, but still not perfect. The customer is going to be changing ISPs.