You could try changing your host server's IP address and see if it still has the same issue (maybe it's added to a hosts file, or perhaps you installed no root firewall?) Can you ping 192.168.68.106 from your server? Not sure if ICMP echo traffic would be blocked by Android however.
Do both your server and phone have the same gateway/subnet mask?
Stock android without an unlocked bootloader will not give you access to the hosts file, and there shouldn't be a firewall you don't know about. Can you run a vbox or live USB on another machine on your network to see if it will see the server?
I just saw you already answered about the same gateway and mask. Hm. I'm thinking there's probably a janky setting on your router, that's the only place I can think of that might have a poorly configured or unconfiugred firewall. Especially if it works on the cellular using the VPN.
Good luck with it, I'm sorry I don't have the exact answer!
Edit - just saw your edit. Computing is like that sometimes! Glad you got it working. π