I'll work on a fix for this, but it still leaves the question of why the ip_tables module is not being loaded on your systems (it is a known problem issue that containers are often unable to load modules and so they needed to be loaded before the container is started). pqarmitage ...
In both cases, we used the ENV VAR as a first way to determine of the Discovery Center activation was actually the root cause, by deactivating it, but it we did not use it as permanent solution (even if that was supported - that would simply have hidden the problem rather the fix it...