My Deco X20 4G router in mobile internet mode (using SIM card) suddenly got a red light and stopped working.

I restarted it several times which did not fix issue. Took out SIM card nad tried it in my mobile phone and it worked there, getting internet connection. So SIM card ok,. Reset the X20 4G router by putting pin in reset hole on the base and went through network setup with Deco App on my phone.

Setup worked until final stage when it said it could not get an internet connection and router light went red. Did this several times but always ended up with red light and no internet connection.

Tried one last time and this time clicked on a link on a setup page that said 'Update carrier profile' or similar. Followed the instructions to update the carrier profile (involved turning off temporary wifi connection to Deco router, doing the update and then connecting again to Deco temporary wifi). This time the network setup worked and the router was able to get an internet connection and the light went green - happy days!

No idea why this was necessary but grateful my router is getting an internet connection via the 4G SIM card again. Posting this in case it helps someone else with the Deco X20 4G router.