@Kidneybean 

Hi,

As for the 6ghz,  Did you mean that you could not see the Wi-Fi 6()802.11ax signal?

And may I know the model numbers of the smart bulbs and wireless printer?

Would there be any error message when they failed to connect?

Here are some suggestions for your reference:

1. Please try to temporarily turn off the 5ghz and leave the 2.4ghz only;
2. Change the wireless security mode to WPA/WPA2(not included wpa3 at this moment);

Thank you very much and wait for your reply.

@Kidneybean 

Hi, the 6Ghz you are talking about here more refers to 802.11ax wireless standard or the new Wi-Fi 6 technology, not a separate wireless signal like 2.4ghz and 5ghz;

The wireless standards on Deco X68 is IEEE 802.11ax/n/b/g capable for 2.4ghz and IEEE 802.11ax/ac/n/a for 5ghz;

So if the clients want to reach Wi-Fi 6 standard, they also need to be 802.11ax capable;

For more details, please have a look at this link: https://community.tp-link.com/en/home/stories/detail/1028

As for the HP printer model 8625, have you set up the static IP address on the printer?

--if yes, please change it to get the IP address automatically;

At the same time, please also turn off the fast roaming and beamforming on the Deco APP;

Thank you very much.