Exchange account shows Disconnected in Outlook 2016

Status bar says Disconnected on my Exchange account. Webmail works, the network is fine and colleagues are connected.

Clicking the status and choosing Work Offline toggle does nothing. Outlook 2016, on premise Exchange 2016.

Since webmail works and others are connected, the fault is between your Outlook and the server rather than the mailbox. Work through these in order:

1

Confirm Work Offline is really off: Send / Receive tab, the Work Offline button should not be highlighted. The status bar toggle you tried sometimes fails to clear it, the ribbon button is authoritative.

2

Test connectivity the way Outlook sees it: Ctrl+right click the Outlook icon in the system tray, choose Test E-mail AutoConfiguration, untick the Guessmart boxes and run. Autodiscover failing here while webmail works points at a stale local XML cache or a DNS change.

3

Clear the Autodiscover cache: close Outlook and delete the contents of %localappdata%\Microsoft\Outlook\16 (the folder holding autodiscover XML files), then restart Outlook.

4

If still disconnected, recreate the profile from Control Panel, Mail, Show Profiles, Add. A profile rebuilt against current Autodiscover settles most stubborn disconnects after server changes.

Ask your admin one question too: whether they recently changed certificates or the Autodiscover DNS record. A certificate name mismatch makes Outlook drop to Disconnected silently while browsers, which handle the certificate differently, keep webmail working. That exact scenario matches your symptoms.

It was the certificate. Admin replaced it last weekend and my machine had the old name cached. Profile rebuild reconnected instantly.

Had the same last month after a VPN client update that broke the proxy settings Outlook uses. Worth checking if the cert angle does not pan out.