After adding a new SIM card, eSIM (SIM Free) suddenly lose signal for long time (Docomo Ahamo / iPhone)

 I have two mobile phone numbers in Japan, one is DOCOMO’s Ahamo and the another one is b-mobile. As mentioned by the telecommunications company, both b-mobile and docomo need to install a profile on the iPhone when first using it, but only b-mobile's profile will affect the APN settings.

One day, when I switched back to the Hong Kong CSL account number, Ahamo suddenly could no longer connect to the telecom provider.

Later, I discovered that the Profile used in the initial setting of b-mobile will have an impact on some eSIMs in use. As long as I remove it, it will be normal.

Possible scenarios:

1. The APN Profile was installed normally. It was working normally, but suddenly one day it became unavailable.

2. APN cannot be used normally after installation

In any case, you should try to clear the old APN Profile first to eliminate obstacles.

Remove Conflict APN Profile

1. [Setting] > [General] > [VPN & Device Management]

2. Select conflict profile (b-mobile for me)

3. Remove Profile

4. Turn on airplane mode for 10 second. and turn off

Profile Download Description

Reference b-mobile profile download: プロファイル・APN設定

Reference ahamo profile download: プロファイル設定方法（iPhone） - Scroll to bottom and click: プロファイルをダウンロード

APN Generator

Also, using APN Generator (https://apn.aseinet.com/) to overwrite an APN setting might work, but I didn't try it.

Reference:

[1] https://www.reddit.com/r/japanlife/comments/14nqfuj/ahamo_sim_not_connecting_to_service/