unable to map network driver outside of ISP windows server 2016

[manny85]

mapped drive resolves while mapped inside of same isp (gvtc) but when mapping from any other isp unable to resolve. all ports on firewall open. where to start troubleshooting?

[DrProfSagi]

so, out of my head i have the following "points of failure"

• DNS - maybe the dns record you have is not accessible outside your ISP due to some port blocking (if you are using fqdn and not ip)
• CIFS has a timeout of 45 / 60 seconds (depends on os), and if the latency exceed that, you will not be able to access your drive.
• If you are using windows server, i assume you want to access a drive that is using domain permissions, so maybe you are not able to validate your credentials vs the DC of your domain outside the isp.
• If by ISP you mean your house vs someone else's house, maybe you are confusing ISP with lan, and you need to check that the ports are open on your router to the wan network
• it might be possible that your ISP is just blocking your traffic, from my experience, ISP don't take it pleasantly when you try to do "commercial" server stuff while paying for a home plan... meaning that they will not open your ports for you without some greens (or whatever your currency is), so if you run out of options, maybe give them a call and ask "hypothetically" what is up with it...