"I tried putting the client PC (IP 192.something) into the Trusted Zone but to no avail" You also have to put the IP address of the gateway pc into the trusted zone of the client pc.HTH.
Huawei P10 review
1995-2015: How technology has changed the world in 20 years
An overview: What leading creative agencies are doing to improve diversity
New iPad, iPhone SE & Red iPhone 7 on sale now
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.