That would be the first thing to check. No need for people trying to resolve an issue that could be fixed in a newer firmware release. Indigo Touch uses mDNS, Domotics Pad does not. So if your router is having an issue with mDNS it will impact Indigo Touch but Domotics Pad will not.
FWIW, it does do discovery using multicast DNS. But still, while it gives some hints that one continues to run, there are plenty opportunities for differences between the hardware and software. I, like others, suspect there is a network issue somewhere.
Patricia, is there any chance that your iPad could be getting in an IP conflict (that is, you have two devices reserved to the same IP address)? It also could be some type of hardware issue, of course. Perhaps a wipe of the iPad would be in order and start fresh?