I have the exact same problem with HiveOn.
eth.hiveon.com:4444
eth.hiveon.com:14444
TLS = Off
Recentry HiveOn moved to a single address mode, not sure it's the new address not recognized
The old adresses are working. See examples in the launch config scripts
eu-eth.hiveon.net 4444
So why is not used? Hive OS configures the miner script with a wizard, first time it happens that is not correct. You can try yourself, impossible to start the miner in the hiveos pool with 1.40