I'm confused. Are you saying you created a second [alias] interface on the same LAN - but with a different subnet (where you intend to statically address clients)?
If so, given it's the same physical network (i.e. no security) - why?
Thats correct, well I just wanted to try to isolate them, I readed aliases can also use their own firewall zone.
I know vlan can be used aswell, but i rather wanted my tvbox reflect the normal lan route from my old original isp box also avoiding having multicast/igmp over the full lan interface.
My isp router is now replaced with the openwrt one.
If your clients are wireless, then you do not need VLANs or aliases, just define different networks and attach separate SSIDs to each one. If you clients are wired, I would use VLANs and isolated ethernet ports.