503 service unavilable

URL please.

Have you asked the host? That is normally a server error message.

Try clearing your cache/cookies on your new computer, restart your modem/router?

So it is a problem with the host or the other pc’s. Unless you have some kind of security software running – I see you have a sign-in limit. How is that set up?

Your login limits sign-in attempts. That could be what is effecting the other pc’s.