Web Server (IIS) Error in DMZ using SMB Mapping Path

Dear Expert,

I have a web application server (hostname as extwebhost) on DMZ. On this DMZ IIS, extwebhost is using SMB protocol to map a share folder from another Internal Host (hostname as webhost) which store my asp.net application files.

For example instead of physically path like D:\ProjectX\WebApp on the IIS, I mapped it using \\host\ProjectX\WebApp.

Everything is working well.

However when I edit the security on the Internal Host (webhost) D:\Projectx\, I will get access error like this printscreen. And it will be working again only after I restart on the extwebhost server in the dmz.

Any advise on how can I solve this problem?

Thank you for reading and helping !
extiis-error.jpg