Both ERA and HC PTR's are down with 0 communication from Blizzard

[Ginzø-dalaran]

PTR Server will be Offline at Times

Please note that we may need to take the PTR realm(s) offline in order to apply priority fixes. We intend to broadcast server messages to testers with a countdown when the PTR realms are being taken offline.

They told you. Perhaps checking the PTR forum every now and then.

Considering they just had connection issues, it is possible they brought them down to focus on live service issues.