Hello,
I am learning on the fly until I can get some training. I upgraded our Multi-Server Test environment from Server 10.2.2 to 10.3.1. I configured the Web Adaptor(s) and now the ArcGIS Server Manger at servername:6080/arcgis/manager/ redirects to servername:6443/arcgis/manager/ .
I also get a certificate error now. Our IT group has upgraded our certificates, but I believe they are only for the external addresses and not the internal addresses to the servers. I am not a DNS, Web, server expert by any means 
I have been doing some reading, but have not had luck yet. 6443 is for https: and 6080 is for http: from my reading. Is this new in 10.3 for 6080 to not work? Server Administrator still works fine at port 6080. Is there anything I actually need to be worried about since it is all inside the firewall and not available to the public. The external site is working fine and I am not having any issues with publishing map services.
Thanks
Chris