Just checked again and I can still get in without fault.
That makes it an environment or region variable, the XAG admin will probably show up and explain that aspect if there is one.
Environmental would be pretty hard to guess at, but assuming Remote Print Services and the App Gallery itself all work without fault, a Wireshark trace would be a good thing to look into. So install Wireshark, enable the trace on the 8070, try to run the app itself, wait for the failure and then stop the trace, download it and open it in Wireshark, have someone knowledgeable in networking look into it (Wireshark is not simple) or call Xerox, get a log created to go to 2nd level and they can help with it. You would need a Configuration report and the wireshark trace, and almost certainly will need to have the issue escalated up further (Won't be quick , first call resolved, 2nd level is not trained in anything related to App Gallery servers and protocols and probably won't know what to look for)
