Could you provide a screen capture, unmodified, of the 'Virtual Machine Settings' for the Red Hat VM in question with the Network Adapter highlighted.
Ordinarily as part of this type investigation, I would have suggested switching the virtual network setting from NAT (VMnet8) to Bridged (VMnet0) but noted that it's been modified [Custom]. As such, as it is not default decided against this as it could possibly open up another whole can of worms.
Its an important part of any investigation to break things down into meaningful and manageable 'chunks', checking each in turn, then progressively verifying and confirming them together. In addition, it is important to peel away any complexity, and starting with the simplest implementation then moving on from there, adding required features and services after testing each in turn. Also ensure a known baseline before starting. Comparisons are also beneficial, such as comparing a working implementation with one that is not, even though they may be differing operating systems but supported by the same underling services. One other frequently overlooked approach is that if a generic error message is produced, then make a change in the relevant area to produce a modified error message, thus confirming the area where the issue may reside. And finally if hitting a brick wall, then try a tangent approach, such as installing a different unrelated popular distro to the one that is at issue, if you have other operating systems VMs that work, this helps with identifying where the issue may reside, and also helps trigger any thought as to what the issue is.
With your setup, all three of the Rad Hat VMs appear to have the same or a similar issue, so there is something common between them. I have many Red Hat VMs, versions, with and without GUI, etc., and have not had any network issues. The only slight irritation, is that in v8.1 with GUI installed, the user interface overrides the /etc config files, such as resolv.conf, but as most corporations don't use the GUI its not really an issue, just worth being aware of and using the network config in the GUI rather then editing the file.
