I've got TP-Link Archer AX55 router and TP-Link RE315 range extender configured as an EasyMesh network.

I've got a Raspberry PI wirelessy connected to the RE315 in the network. 

When I connect to a web page on the PI from a Dell laptop also connected to RE315, I have to connect by IP address.

If I connect to the same web page on the same PI when the Dell is connect to AX55 router, I can do it with the hostname.

Is there a setting I'm missing?  Thanks.