I found that there was indeed an IP conflict. A laptop (ipconfig/all) connected to the TiTo ETH cable showed "duplicate IP" when set to the same static. I'm assuming that a new device was added and the router allocated the IP to that device while the GK was powered off? I changed the setup.ini file and data.htm to reflect a new IP that the router said was free and it works with the android app again. It doesn't show up in the router client list but..

FWIW, I did manage to create an .apk of the bettor app as I got a new phone and the deluxe app is no longer available on the playstore (it was the start of this minor ordeal). If you need to do that as well the "file manager+" app does it via backup mode.
Obviously, I still don't know about the service/add credit question but that isn't really important as long as the app works again.