Unable to access Qnap NAS device

Solution 1:

As a rule of thumb, if you relocate your gear often and you are "guest" on someone's else network (The switch is also connected to a hotel ethernet port...) you should create your own subnet even with a cheap router to be put between your subnet (switch, nas and macbook) ant the external network. This way you control what's happening inside and you mask your devices from the outside, other than aving the possibility to troubleshoot more accurately.

Solution 2:

As others have stated -- it's very likely a network configuration issue. More specifically -- it's like the hotel network you're connect to doesn't allow devices on it's LAN to communicate with one another. This is very common. Considering you're using DHCP assignments from the Hotel's DHCP server, it is also safe to assume you're not using any internal routes between your wired devices.