Hope someone can help with a strange problem.

I have a LAN to LAN set up and connected.
From the remote end I can ping all IP's on the main site (Draytek 2830) with no problem. From the main site end I can ping the router (192.168.15.1) and I can ping the CCTV DVR which is (192.168.15.200) but I cant ping any other IP.
If I go to the remote router (Draytek 2130) I can ping the other IP's but not through VPN.

Trace route one of the other IP addresses gets me to the remote router (192.168.15.1) but no further (request time out).

Why can I ping some IP's but not others? I have defaulted the router and re setup, there are no firewall rule changes from default.
Main site router address is (192.168.16.254)

Thanks.