How to get 2GB with XB8?

Thank you Ray for the prompt reply. 
I have tried to connect to Xfinity modem WiFi (XB8) and I am not getting speed faster than 500mb. It does not drop it is constant between 200mb and 500mb.

I have plugged the TPLINK router in the orange port and the 2.5Gbps port. Then I tried the TPlink WiFi and I get the same results. I have not changed the XB8 to bridge mode. 
thank you. 

You're welcome! You should be seeing that speed when wired as well as on WiFi, BenoitB. You would want to put the modem into Bridge Mode for the router to turn off the internal router in the XB8. Both of them going can cause a whole set of problems. E

ven before that though, the WiFi from the XB8 and wired connection should be up to speed. Let's leave your router out of this for the moment as that does not seem to be the root cause. I need to check how your equipment is listed in our system and the bootfile for the modem. 

Please send us a direct message with your full name and complete service address to “Xfinity Support”. To do so, click on the direct messaging icon located at the top right of this forums page.

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Thanks. message sent

yes please do. Email or Text is fine