WhatsApp offline

Hello to all!

I have a big question and the right replies will help me a lot (more thant you should thinks...)

I live in Italy and Ive a 5g Zte 72A smartphone.

This morning I was on a train and my signal wasn't perfect and I think It's normale during a train trip...

What's happened? That my gf wrote a message, I've replied normale but she goes crazy because, she says, I've modified my status to offline in privacy settings.

I'm an old guy and for me WhatsApp It's like a SMS service upgrade with photos and videos and files uploader and I think It's Always online because you write me and I receive your message. I never changed this setting because first before today I didnt know that and second I didnt modify NOTHING.

How It's possibile that She saw me offline but I was online because Ive never changed my settings? Glitches, bugs, WhatsApp down of two days ago??

Thanks a lot for all replies.