I'm no expert, more linux newbie, but what I read in your post sounded very familiar wrt my SCX-3405W. I have 3 suggestions.
1) URI of ipp://192.168.1.20 (not sure why u changed from ....20 to ...11 in your post)
2) ipp14://192.168.1.20 or ipp14://192.168.1.11
I never needed the ":631/printer" you could try with or without. ipp14 got me printing but not scanning, with the samsung original driver.
3) Install suld-driver-4.00.39
Although not "a recommended driver version on the list of supported printers". I tried the recommended ones, as you did, with limited success. So I took the chance and it worked perfectly for me with "LPD network printer via DNS-SD". Which was the 1st option I tried, so I didn't bother with the rest
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