In Repeater mode, the GL-AR300M works as a router, with LAN and WWAN on different IP subnets and NAT/firewall in-between. If you want WWAN and LAN on the same IP subnet, then you can use Extender network mode.
Regarding Repeater mode for File and Printer sharing, you should be able to at least reach the file server/printer by its IP address on the local LAN, not by its NetBIOS name which cannot traverse subnets/filewall.
Is the file server/printer running on a Windows computer? If so, then the Windows firewall (or Norton or other antivirus firewall) may be blocking access from a different client subnet.
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