This one bit me while roaming in France and it is worth writing down because it masquerades as a network problem when it is actually the device trying to outsmart everyone involved.

The device in question was a ZTE MU5001 5G hotspot on ID Mobile.

In France the MU5001 happily attached to the Three partner network. Signal strength was fine. LTE and 5G indicators behaved as expected. From the outside everything looked healthy. Data, however, was completely dead.

The problem was not coverage, throttling, or roaming being blocked. It was APNs.

The MU5001 decided it knew better and auto populated multiple APN profiles, none of which were correct for ID Mobile roaming. Even after manually fixing things, it would quietly revert back to its own broken configuration. The end result was a device that was fully registered on the network but incapable of passing traffic.

This is the particularly annoying class of failure where authentication works, the radio link is up, but the packet gateway is wrong. From a user perspective it looks like “roaming is broken”. From the network’s point of view everything is technically fine.

The fix was blunt but effective.

I manually set the correct ID Mobile APN, removed or disabled every other profile the MU5001 had invented, then toggled mobile data and roaming off and back on. Once the device stopped being clever, data came straight up.

ID Mobile do actually document this, but only in community threads rather than anywhere obvious or device specific:

No data roaming discussion
https://community.idmobile.co.uk/device-phone-support-26/no-data-roaming-54524

Official ID Mobile APN settings
https://community.idmobile.co.uk/coverage-and-network-support-177/what-are-id-mobile-s-network-settings-45086

The takeaway is simple. If you are using a MU5001 on ID Mobile abroad, have signal but no data, do not assume the network is at fault. Go straight to the APN list and check it line by line. Auto configuration is great until it is confidently wrong.

Sometimes the fastest fix is to stop the device thinking for itself and tell it exactly how the world works.