Might be time to go back to the start
What brand etc is your gateway, ie modem/router
What are its network settings ip's etc
What are your servers ip and dhcp ip settings
Is there anything between the two?
You obviously have connectivity for the management interface to work....
I see you are using iPhones, black magic to me
all my experience to date is with Windows and Android..
HF you have played with Mr Apple and Softether, any ideas?
If you don't mind can I try connecting? email details if you are OK