Connecting fails from internal network behind UTM 9 to foreign UTM 9 via VPN

Question

Hello I have the following problem: if I try to connect from our internal network behind a UTM-9 to a foreign UTM-9 (or other firewall) via VPN, the connection fails with the following error: Wed Apr 24 14:34:48 2019 TCP: connect to [AF_INET]212.xx.xxx.xxx.xxx:4443 failed, will try again in 5 seconds: The system tried to assign a drive with SUBST to a directory located on a drive mapped with JOIN. Here is a small diagram of what I'm trying to achieve: 
 Does anyone know what settings I need to adjust? Kind regards 
 Didier Didier Translated with www.DeepL.com/Translator

DKKDG · Accepted Answer

Hi Didier, 
 this is just the configuration where you set the port from your utm where clients try to connect via vpn. 
 You have to go to Network Protection -> firewall and add a rule for allowing tcp 4443 to the external ip of the foreign utm. 
 Best Regards DKKDG

DKKDG · Answer

Hi Didier, 
 I am not a fan of any objects. 
 Just use them as last resort when you did not know source, service or destination. 
 If you know source, service and destination just build the necessary firewall rule. 
 With any objects you make an hole bigger than necessary in your wall ;) 
 Best Regards 
 DKKDG

DKKDG · Answer

Hi Didier 
 the vpn connection might fail because your firewall does not allow a connection on port 4443. 
 Do you have a firewall rule that allow this kind of traffic? 
 Best Regards DKKDG

BAlfson · Answer

Hallo Didier, 
 Port 4443 is reserved in UTM for access by a SUM (Sophos UTM Manager). You will want to choose a different port for that remote UTM. 
 I believe that wireless providers block UDP and other ports that might be used for VPNs. One reason to stay with the TCP 443 default for the SSL VPN is that your cellular data provider might block UDP. My AT&T iPhone XS was unable to establish a working SSL VPN tunnel when using UDP 443 or UDP 1443. Everything worked perfectly with TCP 443. 
 Cheers - Bob