[PROBLEM] NAS unmount

[Miss Sissy Princess]

8.8.8.8 is a Google DNS server address.
Shouldn't be set on a host sat on a LAN though, would be normally used for setting a router's WAN DNS to avoid the ISP's often slower DNS services.
Either OP's manually configured this in Moode's settings or has set this in their router's DHCP settings. Either way OP's probably misunderstood what DNS is for and how an external dns server is used.

There is nothing wrong with using 8.8.8.8 (or 1.1.1.1) as the DNS server on a host unless you are relying on DNS resolution to "find" local systems by name.  If someone mounts their NAS using its static IP (or pseudo-static IP if their local DHCP server is configured to supply a fixed IP address based on the MAC address of the NAS), DNS does not come into the equation.  That the OP is able to mount the NAS at all would suggest that the problem isn't a DNS issue.