no permissions to access admin page

I cannot access the admin for my site

if i go to /wp-adnin i get the message “you do not have sufficient permissions to access this page”.

however if i then go to the front end i can see the admin bar at the top. again though if i click dashboard i get no access again.

This started happening on my computer first and now the same problem appears on my laptop.

another user also cannot access from their computer but can from their laptop. all users are admin.

this is very confusing,

any ideas anyone?