Are you connecting to the same IP each time with that VPN? A lot of times if you connect to a different IP too rapidly it'll lock your account due to security because it thinks your account is compromised. Once your account is locked you'll have to unlock it
from here
.
My account isn't locked as I can login on my laptop. It's that I still can't login on mobile on my phone. I can't even log in any account. I can't get past: account.jagex.com