A bit more investiagtion shows that the fault is at my end, a new wi-fi router seems to be blocking contact to that (account.otoy.com) network:
ping -4 account.otoy.com
Pinging production-sso-webapp-205421376.us-east-1.elb.amazonaws.com [54.165.202.52] with 32 bytes of data:
Reply from 192.168.225.1: Destination net unreachable.
Reply from 192.168.225.1: Destination net unreachable.
Reply from 192.168.225.1: Destination net unreachable.
Reply from 192.168.225.1: Destination net unreachable.
Swapping to another connection (different wi-fi adapter and different ISP):
ping -4 account.otoy.com
Pinging production-sso-webapp-205421376.us-east-1.elb.amazonaws.com [52.0.136.249] with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Which whilst still looking like an error, isn't really, as pings are often blocked and will time out, but at least the destination is NOT unreachable