@D3nt 

I would check the printer network configuration to make sure it is DHCP. That way the router will provide an IP to the print and place it on the DHCP list which you should then see on the DHCP client list.

@Tony thanks.

Printer is on DHCP, as a matter fact, nothing about the printer changed. The only change in the home network was the new router CX5400 to AX11000.

I even reset the printer back to default, just to re-connect on factory settings and ensure nothing was sticky from the previous router connection - didn't help.

@D3nt 

Here is a cannon support thread of people experiencing the same issues: 

https://community.usa.canon.com/t5/Wireless-Networking/Canon-imageCLASS-MF632Cdw-connected-to-network-but-not/td-p/256193/page/2

Looks like some did what you had mentioned in adding the fixed IP, others modified their firewall.

With respect to the TP-Link router, I would recommend reaching out to our support team.

@Tony Yeah, I just discovered a new problem - Air Play:

Same as with the printer. Older router - CX5400 used to work without a single issue. 

AX11000 - although my TV and my phone are connected on the same WiFi, they DO NOT see each other. Again, tried a few things here and there, but nothing works.

So every device seems to connect; but most of the home network features are simply not working...

Getting super frustrated with this router... might go the "return this junk" route next week. For this much money, the router needs to be smart enough that I don't have to deal with basic setup issues between basic devices. You can't possibly expect someone pay nearly $500 and then spend weeks on Forums figuring this nonsense out...

Possible fix:

1) I changed my two Brother laser printer's IP addresses to a static IP address by providing their MAC address. Six hours after a reboot, got the "No Airprinters found" message.

2) Rebooted the AX11000. Immediately my iPad finds the two Airprinters.

Maybe there is a bug in the DHCP lease time?

See the photo to see how to do this.

@GeoGeo 

Life changing!!! Had issues before and this seems to have done the trick (at least for now)!

Printers, wemo devices, airplay, all would encounter issues here and there. Hopefully this finally makes the top of the line router actually a top of the line router that "just works."

Next up we need firmware for one mesh update!

@GeoGeo You're my hero now

@Obermeister so it appears that this will be temporary, then support gave me the new beta FW below. I've had it for about a month now and it's smooth:

https://static.tp-link.com/beta/2021/202103/20210311/ax11000v1-up-ver1-1-1-P8[20201207-rel86202]_sign_2020-12-08_14.08.30.zip