PowerEdge T40 Tower Server Slowing Down My Internet

Hello Everyone ,

 

i recently purchase a PowerEdge T40 Tower Server  and i am experience a very weird things 

for the start :

i have windows 2019 server standard on it 

i am using Spectrum cable for the internet 1gb down 35 mb up 

i have 8 computers in my office and all the network and internet working great but 5-10 min after i plug my server the entire internet is slowing down drastically, i am getting 400mb down 1.5 mb up 

none of my computer is connected via domain control the only things that my office computer have is a map network drive to the new 2019 server 

i have a stack of 5 static ip's and the office internet connected to a different static wan ip then the server 

things i tried :

first i thought it is the cable internet so i had them change the entire equipment 

i disconnect the office router and connect the server straight to the cable with the same static ip's 

please someone HELP ! 

thank you