Redo the setup of the AE.
Give the 2.4ghz and 5ghz different names, short, no spaces pure alphanumeric.
eg ae24ghz and ae5ghz
Set no security to do the first test.
Set a wireless channel of 11, then 8 then 6 for 2.4ghz .. you can ignore 5ghz.
Attempt to connect the printer to the AE using WDS first attempt.
If this fails.. you have reduced all possible issues to straight incompatible.. it is never going to work.. stop now.
If this works.. now add security, WPA2 Personal.. password 8-12 characters pure alphanumeric mixed case and numbers.
Connect the printer again. WDS first attempt.
If this fails.. try again with WPA1 and 2 .. not WPA2.
If that succeeds it is good enough for now.. if it also fails.. it is never going to work.. stop now.
The solution if you reached a stop now.. is to buy a cheap WAP, a $35 TP-Link N lite wireless router to your AE.. and use it for printer.