Just want to let the community and tp link support know that you can get the subject old workhorse brother laser printers working again -once upgraded to the mesh network.  I had called TP about the inability to connect these great printers ( wiresless works only on 2.4 band) to my new mesh router. They told me that they dont play well with mesh setup and .I was not willing to give up the 5 band for the rest of my recent devices.

I tried a work around by inserting a print server between the mesh and the laser printers. I was able to connect and configure the laser's gui and print a test page but it very quickly lost connection.

I then read up on  the mesh router's Internet of Things (IoT) band.  I engaged that channel in the router setup with just the 2.4 band and disabling the 5basnd.  I was then able to get the 2 lasers working just like before the mesh upgrade and I didnt need to isolate the devices.

Just thought others might benefit from this