After weeding through everything the best option for me was adding in hostName to config.xml.
<preference name="Hostname" value="mydomain.com" />
This has to be the exact domain that your requests are being sent on. Gets tricky with all our test environments.
if you server address is dev.domain.com then the hostname needs to be dev.domain.com.
Not sure if CORS would still be an issue. I set our server to handle it.
We have another newer docker box like this – test-system-docker.user.local:8080
Uses everything before the port for the hostname.
Uninstall any other cookies or xhr plugin i had been using to fix this issue.
If you can I think this is straight forward approach.