I've been trying to figure this out and been running against walls.
I've got a RouterBOARD 962UiGS-5HacT2HnT
I have a ISP that gives me 50 Mb/s internet.
Using the default config, speed tests give me a max of about 25 Mb/s. Yea, I even reset the router to defaults.
So have to use fasttrack to get 50 Mb/s
My problem is, I have been pickup up traffic on the PPPoE connection, running in and out. Sometimes using max bandwidth.
Delving further, I pickup netgear equipment on the DHCP server. I don't have netgear equipment.
It appears that somehow, netgear equipment on the WAN fiber is connecting via the NTU, directing traffic through it. (I think)
I tried to isolate the DHCP from the port, only break my network or internet.
I tried to firewall rules, but that also failed.
I think it is a miss config but everything I tried, I run against a wall.
Bridge is all lan ports in a group. I still need to get to the NTU device to see fiber status.