I have 2 WAC servers behind a load balancer with SSL offloaded to the LB. Both servers report healthy with Get-OfficeWebAppsMachine
Works fine with SharePoint 2013.
When I use it with a remote file, served using HTTP with no authentication (anonymous), I get a generic "Sorry there was a problem and we can't open this document..." error.
In the ULS and event viewer, I see the WOPI error and 501 which basically says:
Could not contact WOPI End Point. Error details - 'NotImplemented url - https://sample-owa-url.com/oh/wopi/files/@/wFileId?wFileId=http%3A%2F%2Fwww%2Blah%2Ecom%2FWordDocument%2Edocx&access_token=1&access_token_ttl=0'.
I also sometimes see this:
<HealthMessage>WordViewerWfeWatchdog reported status for WebWordViewer in category 'WfeRedirect'. Reported status: /default.aspx returned a 404, which means that we didn't have where to redirect.</HealthMessage>
The very interesting part s that I have a dev server, with OWA (WAC) installed, thats not going through a LB and does not use SSL, that works just fine with the same public url word document.