UPDATE: Japanese internet service providers are under a lot of speed stress from many people working at home during the COVID crisis. Make sure you are using IPoE IPv6 service outlined below. A good stress free service is KDDI au Hikari nuro which uses excess bandwidth that KDDI rents directly from NTT dark fiber for nuro.
My father had WiFi problems in his apartment, too many dead spots for a decent FaceTime conversation unless he stayed tethered near his Comcast Xfinity WiFi box. Like most people my father likes to walk around and talk resulting in broken connections and conversations.
I picked up a Linksys Velop mesh WiFi router set for him while in the USA, set bridge mode on his Xfinity box and plugged in the Velop router. It could not have worked out better. All the WiFi dead spots were gone, my father can FaceTime wherever he wanders. Velop truly ‘just works’ out of the box.
Linksys has been absent from Japan for some time but seems to be using Velop to dip a toe back into the Japanese market. Velop is a good product but I do not recommend it for WiFi use in Japan: it’s a poor match for the IPv6 protocols used by Japanese internet providers and the NTT backbone.
Goodbye PPPoE (IPv4) Hello IPoE (IPv6)
The problem with Velop is the same one with the Apple AirPort Extreme (part 1, part 2) and Google Nest WiFi: no support for DS-Lite and Map-E IPv6 protocols. Both DS-Lite and Map-E use IPv6 IPoE (IP over Ethernet) that replaces the older IPv4 only PPPoE connection protocol.
IPoE is also called IPv4 over IPv6. This means IPv4 packets are encapsulated inside IPv6. All internet connections in Japan actually use IPv6. PPPoE/IPv4 is like an old studio backlot, a false front with nothing but IPoE/IPv6 behind it. This means that everything IPv4 has to be encapsulated in IPv6 to travel on the NTT internet backbone.
Any router that does not support IPoE/IPv6 on the internet in Japan does not get priority routing at crucial exchange points between local area lines, the internet provider, and the NTT backbone. PPPoE is worthless because PPPoE/IPv4 in Japan is ‘tapped out’ and sits in a traffic jam on the local internet highway ramp waiting its turn to be encapsulated in IPv6 while IPoE/IPv6 whizzes by on the IPv6 super highway.
Japan Internet Setup
Do yourself a favor and do not waste time and money with any WiFi router that does not support DS-Lite/Map-E protocols and IPoE/IPv6 service. Completely eliminate PPPoE on your home network if you want fast internet service in Japan.
All of the Japanese internet providers offer free ‘v6 Plus’ or ‘IPoE’ service options for connecting your home internet directly with IPv6. I highly recommend adding a free IPv6 option and this is easy to do by phone or online. I also recommend renting a pre-configured WiFi router from your internet provider or purchasing one. If you purchase one, make sure the WiFi router supports the IPv6 DS-Lite and Map-E protocols. The major Japanese WiFi home router manufacturers all support those protocols and maintain IPv6/IPoE lists of internet providers and services qualified with their WiFi equipment:
Always make sure your WiFi router is updated with the latest firmware.
If you are not a DIY networking guru, save time by renting a pre-configured WiFi router from your Japanese internet service provider. Rental prices vary, So-Net for example charges ¥400 a month. If you are in Japan for the long-term and futzing with internet configurations is not a problem, a good WiFi router investment from the list above can save you money.