Singapore and Japan realms have random high ping instances.

All of the Japan servers are in the same datacenter, so I don't know how what you're describing would happen there. All of your screenshots are for Singapore.

It's likely that you have a bad route for one of the Singapore providers. When this happens again, the best thing to do would be to look in your logs\Client.txt file (inside your Path of Exile install directory). The IP address of the server you've just connected to should be at the bottom of that file.

The line will look like this:

"

2019/02/04 13:22:07 1021609312 dc [INFO Client 18504] Connecting to instance server at 63.251.253.108:6112

Run WinMTR on that IP address for a couple of minutes and post the results here. I will be able to use that info to find out where the problem is being introduced,

The problem looks to start on hop #4:

"

| wtsc3a022.netvigator.com - 0 | 46 | 46 | 1 | 2 | 4 | 3 |
| 63-218-231-41.static.pccwglobal.net - 0 | 46 | 46 | 201 | 202 | 204 | 203 |

This is happening really close to your ISPs end of the trace, so I'm not really able to get in touch with someone myself. I would recommend trying to get in-touch with your ISP, and send them through this troubleshooting information. They should be able to update this route to make things better or contact someone who can.