Problem with Kaltura CE running on Centos 7 playing Videos available with low resolutions

we use Kaltura CE now for about 2 years for playing Videos on our moodle site. We installed Kaltura CE 15.2 as this was the most current version at this time. We applied over the time security updates to Centos 7, but never updated Kaltura. We had no problems within the last 2 years.
After applying the last security updates to centos 7 some days before and rebooting the server, everything looks fine, but than users begna to complain that they were not able to play some videos.
They see the rotating logo for some time and then an error message is shown
We digged into this problem and found out that all videos, that are available in low resolutions (beginning with Basic and SD´) are affected, all other videos available only in ‘HD’ are still playing.
If we delete all Basic and SD flavors from a video it is playable again.

We rollbacked the centos updates, but the problem persists. We upgraded Kaltura to V16, 17 and than 18, no changes. I installed a whole new Centos 7 machine and made a fresh install of Kaltura 18 and this system shows the same behaviour. A manual upgrade to the latest 19.4 shows the same problems.

So we think the problem must be caused by one of the last changes to the Centos 7 system. For further investigations it would be interesting to know which Kaltura components are involved in the decision which flavour is delivered to the clients.

The sanity script show no errors besides the DWH cycle, and we are not able to find anything related in the kaltura logs.

Any help or idea is really appreciated.

We found the problem, the nginx certificate was expired. Interesting, only with existing basic or sd flavors the nginx url is called when playing a video.

Our test system is a clone from the prod system. We run teh config-all script with the new system name, but when playing a video in the preview window the original url from the prod system was called and therefore we run into the same problem, although the nginx certificate on the clone system was valid.

On the new system the url called when playing a video uses https and port 88, the non ssl nginx port and also fails to connect.

3 systems, 3 different problems, always the same error. To examine only with browser inspection.