Hi,

I have a problem using VPN PPTP for my Office. here is a topology for my network office


i don't have any static public IP so i use IP >> Cloud feature for this VPN network. but i cannot using DNS name to connect the network from the outside.

Someone has solution for that ?

Can you ping the DNS you try to connect to? If not, check the routers DNS server.
Also are there any firewall rules, that block PPTP input on the HQ Mikrotik?
Is there any firewall on modem 192.168.2.1?

First of all: in which IP address resolves your domain from router or your computer? nslookup or smth
Second: Did you open tcp 1723 port to MIkrotik PPTP server? If IP address of your ISP terminates on your router modem, the you should allow forwarding this port to IP address 192.168.2.3 with NAT address port translation. If your router modem simply bridged with Tik port, just accept in input chain tcp port 1723. Most likely IP address of ISP belongs to router modem, then you should do NAT translation to Tik WAN address.