RBS750 satellite will only get 100Mbps on wired backhaul
I am having a very similar issue.
RBR-750 with two RBS750. Both satellites are hard wired for backhaul.
Cable modem->RBR750->Netgear switch->RBS750s
I connect my work laptop via Ethernet to my one satellite and always had >500M speeds. This week I noticed my wired connection not getting any faster than 98M. I have tried many of the same troubleshooting steps you have tried.
My warranty is already up, following to see if you get any other solution tips. Thanks.
Re: RBS750 satellite will only get 100Mbps on wired backhaul
Ethernet speed just slightly under 100Mbs almost certainly reflects that a link in the path has negotiated a speed of 100MB/Full rather than 1000MB/Full. Determining which link is not easy. In this situation, there are probably three Ethernet links with a total of (probably ) five Ethernet cables:
RBR750 router to switch. (one patch cable)
Switch to RBS750 Satellite (three cables)
Patch cable to wall jack
Ethernet cable through building to location of satellite.
Patch cable from wall jack to satellite.
Patch cable from satellite to laptop.
The RBR750 will report the speed negotiated with the switch on the web browser interface, Advanced Tab. Select the blue box Show Statistics to display the speed the router has detected to the WAN port and any LAN ports that are connected to something.
The switch (and maybe the laptop) usually have tiny LEDs on each Ethernet port that display the speed and activity.
In addition, the laptop will usually report the connection speed of the Ethernet adapter in Advanced Settings (buried in the LAN adapter information). (It annoys me that Netgear did not include those tiny LEDs on the router and satellite, but I understand why they did not. 1. The ports are on the back of the case. 2. Customers would be annoyed by blinking red and green LED in the bedroom.)
100MB/Full Duplex uses four of the eight wires (two pairs). 1000MB/Full uses all eight wires (four pairs). If even one tiny wire does not make good contact, the speed will drop from 1000MB/Full to 100MB/Full.
If the laptop is carried around and plugged into the satellite at times, my first thought would be to examine the Ethernet cable that is connecting it to the satellite. (It is not all that easy to see those tiny wires inside the RJ45 jacks.)
Another diagnostic step might be to swap the two satellites and see if the problem "follows" the hardware.
