When he was a little boy, Sam Vimes had thought that the very rich ate off gold plates and lived in marble houses.

He’d learned something new: the very very rich could afford to be poor. Sybil Ramkin lived in the kind of poverty that was only available to the very rich, a poverty approached from the other side. Women who were merely well-off saved up and bought dresses made of silk edged with lace and pearls, but Lady Ramkin was so rich she could afford to stomp around the place in rubber boots and a tweed skirt that had belonged to her mother. She was so rich she could afford to live on biscuits and cheese sandwiches. She was so rich she lived in three rooms in a thirty-four-roomed mansion; the rest of them were full of very expensive and very old furniture, covered in dust sheets.

From Men At Arms by Terry Pratchett

Have you tried pinging a known external IP (e.g. 8.8.8.8) to see if it’s visible from the LAN devices? It could be something as simple as DNS not being setup correctly. Also, have you verified that the LAN devices are being assigned an address?