MAC address fails to connect via wifi. and what is MAC address??

I think there are 6 ways (at least?) to connect this printer:
(1) Direct to Mac (or PC) via USB Cable (2) Direct to Mac (or PC) via Ethernet Crossover Cable(3) Ethernet to router/switch, with Mac/PC also via Ethernet to router/switch(4) Ethernet to router/switch, with Mac/PC via WiFi (802.11 wireless)(5) WiFi to router, with Mac/PC via Ethernet to router/switch(6) WiFi to router, with Mac/PC also via WiFi.
As (1) should be simplest, tried this first. First document would print instantly and completely, next doc would hang in queue with unexpected msg, "Printer is offline." Only way to print 2nd doc was to power cycle (off-on) the printer. This problem occurred whether 2nd doc was sent to printer before or after 1st doc had printed. Tried 2nd USB cable, tried new driver, tried reinstalling printer; same problem. Spoke to both Samsung and Apple support, including both on a conference call; never got this to work and never clarified if problem was in printer hardware/software, driver, or something else. Both companies now showing this issue as unresolved.
Nothwithstanding USB problem, did succeed in modes (4) and (6), although custom wireless config needed since my network does not broadcast SSID and requires an encryption password. Procedure required connecting first via Ethernet, obtaining Configuration Report by holding down orange button for 5 seconds, then using browser to connect to the printer's IP address. Also required different driver for wireless config (as opposed to USB).
Bottom line: What seemed simple - USB direct connect - proved unworkable, but wired and wireless network config works fine.