Hello,
We use Mikrotik 750g as a VPN server. My question is how connect server or some PC on internet over port 4?
Hoe can i open thi port?
Thanks
We will need more information about your setup. 
ok 
we have public ip from some ISP, ruter with static ip is connected on MikroTik port 1.
Port 1 is configured as WAN port. (there is some public ip)
Port 2 is configured as a LAN port and is connected to a network switch (the network switch is connected to ADSL)
Server is connected on ADSL .
When there is no internet connection to ADSL other clients can not connect to the server via VPN.
What I want to achieve is that the server has a connection to internet through mikrotik because it is much more stable,
i want to remove server with adsl and connect it to the mikrotik.
If you need more info, i can send to you sheme of network.
I hope I explained well.
Go ahead and send your diagram along with /ip address export /ip firewall export /interface export
I am not currently able to make export ip address from RB750G, I have only diagram how is connected on the location and scaned picture with some ip adresses.
Can anyone help?
Sounds like you just need to re-configure the server to use the Mikrotik as a default gateway and remove the ADSL modem. I don’t see how any changes on the router are necessary.
If you need to add another network to the router - I’m not sure if that’s what you’re asking - just set the master-port of that interface to ‘none’ and treat it like any other new LAN network port: add an IP address, make sure it fits your source NAT rules out to the Internet, and configure DHCP if necessary.
http://wiki.mikrotik.com/wiki/How_to_configure_a_home_router
ADSL must stay as it is.
I need Connect server to mikrotik, server must have internet connection over mikrotik beacuse he is much stable than ADSL.
I guess I don’t understand what you’re asking. According to your network diagram the server is already on a broadcast domain with the Mikrotik router, the only thing in the way is a switch. So just change the default gateway on the server to be the Mikrotik router. Done. Though at that point I don’t understand what the ADSL modem is doing anymore.
ADSL is internet for another 20 computers. Beacuse public ip gas speed only 1/1 mbit
OK. So does the Mikrotik router have an IP address on the network the server has an IP address on? According to your diagram it does.
Set the server’s default gateway to the router’s IP address on the same network. That’s it.