no it is not, though there are edge cases (i think, maybe outdated info) where if your LAN subnet doesn't start with 192.168. that the server would treat you as a non-local client. you can try something like nimbul's external local bundle loader (linked below) to try to build a local cache and see if that fixes it.
https://github.com/nimbuldev/SPT-External-Local-Bundle-Loader/releases/