Hi,
we have a router with microtik routerOS, workin in a hotel for WLAN for the guests. Unfortunately does VPN not work properly. So if a guest tries to to connect from his notebook via our WLAN to his company LAN via VPN it does not work.
What could be the problem?
You have to give more detailed problems description, at least provide us with used VPN protoco name.
I can assume that PPTP is used at client machine, if NAT is used on your router enable (pptp and gre helpers at 'ip firewall service-port), either provide us with more details about your scenario.
Try unblocking port 10000 if your blocking it. I know Cisco uses it on their VPN client.