First, I am assigning this to "Networking" like other dns2go questioners have done, but if there are better topics to assign it to please advise!
I have a simple setup in my office with three PCs running DCHP on a Comcast router. No server, no domain, everything straightforward simple.
I also have a PC on a static IP address of xxx.297.242.67 we lease from Comcast that is running Robo-FTP server for about 100 clients who back up to this PC. That setup has been working fine for years. But I need to change to a different ISP who does not offer static IPs so I am trying to find a way to make that work.
When I set up a Robo-FTP client I do not use the static IP address of xxx.297.242.67 because I subscribe to the dns2go.com service. I "could" use that static IP address, but the address xxx.dns2go.com we use from dns2go is easier to remember--plus it worked very well for us when we moved from one city to another where the static IPs were different. This is because the dns2go service running on this PC connects to the dns2go server using our current static IP address.
(If it would help for me to provide our full static IP address and dns2go name, first I just need someone to tell me if that is considered legit (and safe) here on E-E .)
So this backup PC is currently configured for its static IP xxx.297.242.67 and that's what the dns2go server sees as well. The first thing I tried was to configure the network card for this PC to DHCP like all our other PCs, and indeed it gave it a 10.1.10.x address. Then when I checked the status on the dns2go server it showed an IP address for this PC at xxx.297.242.70 which is our gateway address. The dns2go service on this PC connects to the dns2go server just fine.
But the problem is that the Robo-FTP clients can no longer connect to my Robo-FTP server. So I sent a tech support request to dns2go.com asking if this should still be able to work without a static IP...because I thought that was the whole point of a service like dns2go, where it could "find" the PC no matter what it's IP address is. Below is their response:
Yes, you should be able to utilize a dynamic IP address assigned by your ISP for what you are describing.
Where is the static IP address you are paying for presently configured?
On the backup PC or on a public interface of an Internet router?
What protocol does the backup process utilize?
What ports TCP and/or UDP does the backup process utilize?
The only reason why it might not work is if your ISP blocks certain inbound ports on dynamically assigned IP addresses.
After they asked me about protocols and TCP and UDP info, I wrote to Robo-FTP tech support and they gave me that info. But now it occurs to me that no matter what those answers are, it seems like it should still work with the PC now on my local LAN since it worked when it was assigned to the static IP. Is that correct?
And then they said that the ISP might block certain inbound ports in dynamically assigned IP addresses, I don't understand how I would find that out. I do know there is no firewall turned on in the Comcast router, and during my testing I had the Norton firewall turned off on this PC. Of course I could assign a static IP in the 10.1.10.,x subnet but I can't imagine that helping...right?
Furthermore, even if I find someone at Comcast tech support who can figure this out, my end goal is for this to all work with a different ISP who offers nothing but dynamic IP addresses, and worse yet it is in a city 1000 miles away--so if I ship it there and it doesn't work I'm up a creek.
What I'm really hoping that someone here can make sense of all this, and tell me not only how to get it working here on my current Comcast setup, but helping me insure that it will work with the ISP 1000 miles away--and how to do so. Or if the whole thing is hopeless without a static IP then I need to know that. TIA