@Phanish 

Hi, welcome to the community.

Were you still troubled by the slow speed on Deco X20?

If yes, could you please help me check the following information:

1."The max speed I get is 40mbps", Do you test the speed via 5ghz from main Deco, or via Ethernet connection?

--please also check the link speed on the tested device:

2. Please check the Qos settings under Homeshield and make sure it is disabled or set to be 1000/1000 m/s download and upload.

3. Turn off the UPNP feature and SIP ALG feature in Deco APP>>>MORE>>>Advanced menu.

By the way, May I know the model number of your ZTE modem?

Thank you very much.

Best regards.

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