Based on your follow up, I'm guessing you may have had an older version of the service worker cached as there was a time earlier in the beta where the offline message may have come up instead of the browser returning a more reasonable error. So it was probably the SSL error that got masked. It shouldn't really happen with a more recent service worker involved.
In terms of redirects, we don't automatically redirect. If you want it to redirect, use the ACP search for "boardUrlCanonical" though note the caveat in the description.