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It seems i managed to get Spotify Connect back on X4100w by Initializing the network adapter (from remote go to Online Music then on AVR console hold down DIMMER + > buttons for min 3 sec). Other DENON AVRs can initialize network adapter by combinations listed here http://denon-uk.custhelp.com/app/answers/detail/a_id/3848/kw/reset%20network
PS. i use WIRED LAN connetion, fixed IP (DHCP is OFF), default gateway is the router IP (mine is 192.168.1.1); DNS 18.104.22.168; second DNS 22.214.171.124
Good luck and hope above helps.