Outlook on the Web - no Preview option in IE

[3s-gtech]

Hi all, This is a slightly niche issue, but it'll nag at me. In Outlook on the Web 2016 (OWA 2016 by another name) I have set up Office Online Server to serve attachment previews. This works fine on my PC, other than some certificate quirks in Firefox and Chrome (it's a CA cert). It works perfectly in IE. Now, when I log on as a domain user, the Preview button and the ability to preview the file through Office Online disappears - it just gives the normal file download prompt. This obviously isn't the end of the world, but I can't find what's causing it - compatibility view is off, I've tried a new Internet Options configuration via GPP. Any ideas? More info: happens on all computers other than mine, whether domain user or not! Really odd this one. Certs are trusted and pushed out via GP, same on both. Same proxy.

Edited January 23, 2019 by 3s-gtech

[3s-gtech]

Seems to be related to the lack of an external URL specified for the Office Online farm. Wasn’t needed in 2013. So it works for Skype still, allowing Powerpoint sharing which is the most important bit. It also works in Firefox, Chrome and IE on my PC (but not IE elsewhere). Looks like to get it working reliably in Exchange I’ll need the server to have an external IP and a Let’s Encrypt cert, which is far more work!

[3s-gtech]

Self fixed (it seems). Going round in circles this morning between getting SfB to work with it and Exchange 2016. Re-created the farm using the internal URL as the external (this will break for users off network). That can be sorted. Then made a new certificate, updated SfB, reinstalled Office Online Server, removed the Allowed list of domains from OOS, restarted IIS, and it finally kicked into life. One of those things that's 100x easier with O365!