DCS Server specific - Cant connect to my own server using External IP Address

[PSYKOnz]

Hi all, hope you are well, I'm having a bit of a weird connection issue connecting to my DCS OB Server.

off the bat this issue only affects the DCS OB Server, no other servers are affected 

so what's happening?

I run a small server for me and my friends to play games on, for network security, I have the server machine on a dedicated "guest" network that is separate from all other networks with no LAN/Intranet access, due to this setting I have to use my external IP address to connect to the server rather than the servers internal IP address. this is no trouble at all for my Arma 3 and Arma reforger servers with them I punch in the External IP and boom, connect easily, however, the DCS Server is not so lucky. If I put in the IP and Port in it it goes through to a generic loading screen but does not click over to the server loading screen and I can not see the PC trying to connect on the server dashboard. after the first attempt the ip connect option will not work again, however, I am now able to see the server in the server list (I should note at this point that the server is not public, we connect via IP) if I click on the server now listed in the server list it attempts to connect but won't connect and I do not see an attempted connection in the dashboard, same behavior as the first time I try to IP connect.

again this is only an issue for DCS, other servers hosted on the same machine have no issue connecting at all.

some more info...

I only run one server at a time so when DCS is up only DCS is, none of the other servers, so there's no conflict there

the correct ports are opened and forwarded, as other players can connect regardless of my connection method or issues

other players are successfully connecting and playing using the exact same external IP that I am unable to connect with. had 6 on during one of the tests I did, and none of them had issues

the "guest" network only has an access point and the server on it, nothing else

I can connect to the server if I use a VPN on my PC, not an option I want to use

The server has a static IP that works regardless of the connection type

I can connect if I remove the LAN/Intranet Restriction on the "Guest" network, this just puts the server on the LAN and I can connect using the internal IP address, and this defeats the point of the security Im trying to keep

I can also connect if I move the connection to a slot on my switch which is on a completely separate VLAN to my PC (I have to use the External IP to connect, not internal as it's on a separate VLAN)

and of cores, I can connect if I put it on the same LAN as the PC (external or internal IP works this way)

again, I do not have any of these issues with the other servers I host, I can connect to them on the separate "Guest" network using the external IP with no issues at all

so as you can see it connects fine unless I'm using the separate "guest" network WITH the LAN restriction, I'm not sure where to go or what the issue could be

any help or ideas are greatly appreciated, I'm not really sure what is going on or why, it's a bit weird

anyway, hopefully someone here can help me, or at least report this as a bug maybe?

Cheers guys