In my house I have a Zywall 5 router and an airport express for wifi. When I try connect to spotify I get the message "You are offline. connect to internet and try again. I have no problem connecting to internet with Safari. same thing happens at work where we also have a zyxel router.
No problems connecting at flat in town where I have a TP-link router and also an airport express for wifi or on mobile 4G network. Are there any known issues with zyxel routers and spotify?