Info:

MikroTik 751U-2HnD setup as Wireless AP, 2467, 2Ghz-B/G/N, 20Mhz. No issues until recently. I was in NOVA at my grandparents for a week and he also has the same router with the same configuration, I had no issues before I left and no issues while I was there, but when I got back home my GS3 will not detect the 751U.

My laptop does, and it works perfectly. No settings have changed on the MikroTik router, but I'm stumped as to why the phone won't detect it. It detects the other 2Ghz router and the 5Ghz router just fine.

Any suggestions?

Try deleting the other wireless network. I've seen this before on a laptop. It wouldn't go away until I removed the other wireless network.