[Windows Central Question]

Good morning to all
Ive changed my Lumia 630 DS to a Lumia 640 XL DS not lte.
Ive used a Nanosim card for my 3g/2g flat rate and another one from the same operator to make calls.
Im under WP 8.1 and all is updated.
For me, both sim cards have stopped. In the cellular menu +sim, I cannot find my sim cards.
Indeed, its displayed in grey Sim 1 setting , sim card one, and its the same for im 2.
I cant put my phone in plane mode, and I have then to restart my device. It works fine for a time and and restarts again.
Ive changed my internet sim card, but the problem persists. Ive permuted the Sim cards,,, its the same.

[roi_noir]

sorry I forget to add :
" What I must do ? change the device ? the sim cards ? or other thing ?

Thanks "