Oh my god you're right, I'm dumb today. Anyway I was searching the internet about IoT security and I found a guy, who set up VLAN in ASUS-Merlin, so it should be possible even with my other requests. I'm still gonna stick with Synology. I don't have that much IoT devices and at least in my country, it's fairly new thing. Maybe someday in a near future, I'll set up a different network for my devices.