I think Ireland should be reminded that an hard border could be a no issue for most of EU members, as it would impact only a few counties there, and there are already hard borders in EU along areas with common ethnic/cultural environments - think about the Polish and Rumanian border to the East. While UK is evidently using it as a lever to obtain a better deal in Brexit negotiations. So why EU should care about a wholly Irish problem, when Ireland shows again and again it doesn't care about others problems?