Question Network switch reduces Internet speed

[tonys44]

I have the Altice One system as my ISP. The Altice One uses a master cable box that is a modem, router and TV controller in one. It has 4 LAN ports. When I connect my computer directly to the box, I get a speed of over 400 MBps. I want to split the line using a network switch, but when I connect the switch, the internet speed slows to around 100 MBps. I have never had that problem with other systems in the past. Is this unique to this type of system, or am I missing something? I expected minor speed degradation, but not a 75% drop. I want to split the signal where the switch is to power a PoE camera but do not want to lose the speed. Calls to Altice provided no answers.
Thanks.

 

[USAFRet]

What is the exact make/model of the switch?
Possibly it only has 10/100 ports.

 

[tonys44]

Thanks for your quick reply. It is a TP-Link TL-SF1005P and you are correct. I neglected to read it carefully. It is 10/100. I guess I need to put the glasses on. Thanks again for showing me the forest, when I was staring at the trees.