@SeptemberC 

I assume your printer is connected to the Linksys router.

I assume the Deco operation mode is "Router", the default.

What are the local IP addresses of a device connected to the Deco and a device connected to the Linksys router?  That should be visible in the Deco and Linksys apps.

I believe you have to change the configuration of either the Deco, either the Linksys, to let them work in "Access Point" mode.
I suggest doing that on the Linksys.  If I read well, they call it "bridge mode".  https://www.linksys.com/support-article?articleNum=137888  You an choose the "DHCP" option for the IP address of the router.

If you want to do that on the Deco, this is via the "Advanced" setting, under "Operation Mode".

  @yves_b 

Luckily I have resolved my issues.  Unfortunately I didn't write down all of those ip addresses down.  (They started off with 10.xxx.xx) The router I was using (EA7450), I had turned off DHCP and the WAN.  I was having the same issues even when I used a netgear switch.

I resolved my issue by using and old Linksys Router EA7300 that had the option to set up as "bridge mode".  I turned off all devices. Current set up is Cable modem ---- Deco--- Linksys (EA7300).  Powered them back up in that order, then started powering up all other devices in my home.  Now it works flawlessly.