If you're using the wired Ethernet port, it is 10/100 -- not gigabit.  So if you're seeing 90 Mbps, that's probably about right. If you want the full 200 MBps, you will need to use a USB 3.0 gigabit Ethernet adapter. Documentation here: [URL]  
I have upgraded my internet speed to 200 MBs and by doing a speed test on my Inspirion 5755 I can only get around 90+ MBs. Xfinity saying my laptop is an issue as it does not handle the faster speed. I have searched and found that the link speed is set to 100/100 on my network settings. I have tried other info provided on the Dell community page and have not been able to resolve the issue. Any help in this area would be of great help.  
Link Speed 100/100