ORBI LTE won't connect with SMARTY sim.

My ORBI LBR20 has been working well with an existing SMARTY sim. I have tried to change to a new sim on a different plan but on installation ORBI says SIM not present or rejected. Old SIM still works when swap it back, new sim works in my huawei router, I’ve reset the ORBI to factory settings twice and made sure firmaware updated. I’ve changed APN to that provided by SMARTY and changed PDP to PDP-IPv4v6. SMARTY online support being pretty useless other than sending me a replacement SIM but sure that's not the issue! I remember having similar issues when I got the ORBI initially (ie in using the SMARTY sim with it) but think the support that was provided as a new purchase managed to get it sorted. Help please!!