Cannot send any SMS

[whatever]

I cannot send any SMS from my Murena Terracube 2e. I’m running e os version 2.0.
I have tried with two different sim cards, from different countries, and nothing works.
I’ve been using this phone for a few years. It started with not being able to SMS any images a few weeks ago. Now, no SMS’s work. They all say “SMS failed. Tap to try again”. Nothing happens.
I can make calls and get Internet access on this device.
I can receive SMS.
I’ve rebooted the phone, swapped sim cards, and all of the software is up to date.

[loki]

I’ve the same problem in France on a Xiaomi MI 8 since December, that’s a big problem.
you can send SMS by disabling 4G in parameters, if 3G is still available in your area.

[obacht]

Have you doublechecked your current APN-settings to make sure they match with what your mobile phone provider recommends?
Sysem settings → network/internet → mobile network → (scroll down + expand) → APN

[loki]

I updated to v2.1 and i now can send SMS in 4g back again.
If you still have problems check the APN settings of your provider as mentioned by @obacht

Edit (for Free customers and /e/ team):
For my problem maybe it was resolved after I came back to a normal phone plan from my provider (Free in France). I couldn’t send SMS after i had had a digital plan overrun, that stopped my 4G connections (after 20 euros were taken for some bandwidth). Then at the end of that month they updated my 4G plan automatically a bit (i had to pay) for some months (“boost” option from Free). recently i came back to cheaper plan, and maybe this is why I can send SMS back as it happened at the same time as the 2.1 update. I couldn’t say what solved the problem between the two.

[whatever]

I don’t know what was causing this, but we can close this thread, because it’s miraculously working again. (I wasn’t able to follow-up sooner because I was out of the country).
I’ll be sure to do a much more thorough job troubleshooting next time this issue arises.