Roaming in Japan didn’t work

[AndrewTraveller]

I was in Tokyo and Nagoya recently on holiday but couldn’t get a usable data connection at any time, although it did briefly connect a few times. O2 have charged me £15 for 3 days of the bolt on use, so wasted money for me. I searched O2 for any special settings needed, nothing needed apparently. So don’t rely on it working. A local data portable wifi sim was great though.

[pgn]

Did you search for a local carrier manually? 

• Forbidden Networks: If you're struggling to connect to any of the roaming networks showing as available, another option is to try and manually connect to any networks showing as forbidden.

One of just many tips in Guide: Roaming MegaGuide 

If nothing at all worked, other tips are here for your next trip, @AndrewTraveller 

• If you use an iPhone: Check your phone's APN, https://support.apple.com/en-gb/102483 , is "mobile.o2.co.uk" instead of idata.o2.co.uk (something was missed by O2 when your account was set up, and idata is missing on O2 side).
• Make sure you are using 4G (5G should work too).
• Ensure you have Data Roaming enabled (as well as roaming).

[madasaf1sh]

Never had any problems roaming in Japan on the 4 times I have been, apart from people calling at 3am in the morning 😞 

What network where you trying to connect to? Did you try and connect to a different network and turn off 5G (as you won't connect)...

[jonsie]

Only been to Tokyo in Japan but likewise had no problems roaming on O2

Maybe OP has an iphone with incorrect APN?