So, I contacted SE...
I gave them my IP address and they told me that the address has been restricted and I needed to contact my internet service provider. SE also gave me a list of port numbers that needed to be unrestricted in order to connect to POL. According to SE, once I contacted my internet provider and gave them the port numbers, the connection problem would be solved. The numbers were:
I use KT for my internet access, so I contacted them. The English customer service center seemed to be able to understand my problem, and they are sending a technician to my apartment today (Saturday) at 5:00 to check my port connections.
I also informed KT that this was not an isolated incident with me, and that others in Korea are also having the same problem.
For now, I'll just have to wait until the technician arrives to see what they will do about this. I assumed, perhaps incorrectly, that if I gave KT the port numbers over the phone they would be able to "switch" them on and all would be right in the world again. But, I guess it's not that easy.
I was also informed that the technician will not speak English, so this should be fun...