Can't connect to my WD My Book World edition

Older dialect LAN? :grinning:
Nah, TCP/IP has not changed for ages, unless you router is IPv6. Unheard off for Home LANs. For WAN possible.

However, there have been reports on some of the newer WD’s NAS devices, not being visible after getting a new router from ISP. Get a switch in between and see if it helps as mentioned in Can't connect My Cloud Using ATT Uverse 1Gig Fiber Service.