Server with specified host name not found

Platform, device version and operating system
Apple iPad Pro 12.9in. IOS 11.2.6

Screenshot or image

What you were expecting to happen, and what actually happened
Just finished PvP, expecting the win screen but I get the “Server with specified host name not found”.
Nothing seems to happen when I tap the screen. I try to clear the screen multiple times but nothing happens. I end up having to terminate the app and start again.

How often does this happen? When did it begin happening?
Happens quite often, so far mostly in PvP but also a couple of times in Dungeon.
Probably about 10 times by now, which is why I thought I would report it.

Steps to make it happen again
It seems to be intermittent. Happens in different PvP battles with different enemies, etc.