Outlook tends to have trouble if it can't make the connections it wants, even if the user doesn't.
Disconnecting Outlook from Exchange generally needs to be initiated from Exchange.
Have you tried setting the Exchange box in Cached Mode? At least that would make it stop looking for the server until online status is reinstated.
1.From the Tools menu, select Email Accounts... .
2.In the window that opens, under "Email", make sure View or change existing email accounts is selected, and then click Next.
3.Highlight your Exchange server account, and click Change... .
4.To turn Cached Exchange Mode on or off, under "Microsoft Exchange Server:", check or uncheck Cached Exchange Mode. Click Next, and in the window that opens, click OK.
5.Click Finish. Restart Outlook for the change to take effect.
Advise if this helps.