Router/nas no connection

[Enquiries]

Gave my daughter old synology ds15j, clean wipe. Plug in to her sky router no flashing lights on the lan or on Ethernet cable, so laptop shows nothing. Using same Ethernet cable plug nas directly to laptop everything is fine proving nas & Ethernet cable is ok. It’s like the router is blocking the nas. I have a new synology & ok, old one works on my router ok, just my daughters sky router nothing, ideas ?