Hi ​@007bee 

Thank you for getting in touch with us. 

I understand why that seems confusing. When you're in the UK, your phone connects to our local network, which can be affected by factors such as network congestion, signal strength, coverage in your area, or temporary faults. When you're roaming, your device connects to a partner network in the country you're visiting, and that network may have more available capacity or stronger coverage where you are, resulting in faster speeds.

In the meantime, you can check the coverage in your area using the link below:
https://www.idmobile.co.uk/help-and-advice/coverage

You may also find it helpful to try the following steps:

Reinsert your SIM card
Try your SIM in another phone
This will help determine whether the issue is related to your handset or the SIM card.

For iPhone (iOS) – Reset Network Settings:
Go to Settings → General.
Tap Transfer or Reset iPhone → Reset → Reset Network Settings.
Confirm the reset when prompted.
Once complete, return to the home screen and restart your iPhone.

For Samsung – Reset Network Settings:
From the Home screen, swipe up to access Apps → Settings → Connections → Mobile Networks → Network Operators.
Turn Select Automatically on or off.
Alternatively:
Go to Settings → General Management → Reset → Reset Network Settings.
Confirm by tapping Reset Settings.

Thank you,

Zandile 

The iD Mobile Team