@Yokushka  this is not how multicast works. you have created 2 separate networks and now wonder why they do not behave as 1?

@Ricky666 
App is aware about controlled devices IP addresses, so why do you need multicast in this particular case? Technology should be used wisely.
Have a great day.
 

@Yokushka because without announcing itself via igmp a client will never be discoverable

you cannot have the 2 *TOTALLY* separate networks without forwarding ports around. that's the whole point :-/

@Ricky666 
Client devices are already registered and not required to be discovered. What is not clear for you in this statement? Why do you repeat the same phrase again and again without reading original message? Tunneling between subnets is a simple firewall rule, which even not required in many vendors. 

@Yokushka everything. so you want to be kasa device vlan2... kasa app vlan1... and want the cloud to control? simply configure your switchgear properly. you want *local* control across vlans? nope. this is not how networking works

@Ricky666 
My dear friend, when you finish school, you will find that it is not good for security reason to keep your IOT devices and the rest of devices on the same network. Yes, many customers don't care, but at the same time they don't buy smart devices or they hire professionals to install them. For security reason people have at least 3 networks at home, guest, iot and main one. And some have more - this is THE standard these days. 
If it doesn't work for you, it is ok, I understand your life is full of magic, but there is always a time to learn.

Happy learning.

@Yokushka do it with subnets, not vlans. yes... good luck with your 2 totally 100% separate networks. that join up in the middle. *think* 1st. type 2nd, my friend :-)

@Ricky666 
Ok, I see your misunderstanding. 
A virtual LAN (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer - Layer 2, based on MAC addresses of clients
A subnetwork or subnet is a logical subdivision of an IP network - Layer 3.
Often, when speaking about subnetworks behind the same router, vlan term is used to point that different domains are used. In my original message I mentioned about client IPs, which means Layer 3. So yes, should be done on Layer 3. And don't tell me switch has no idea about IP based on used hardware. And please, read carefully what is written, there is every word matters. 

@Yokushka yeah you could ger the basic terminology correct before going a little crazy maybe :-)

it does work over level 3. indeed as you so quickly jump at... i have my kasa things on a new subnet for any potential risks

you may need a mdns redirect or reflector to your 2nd 'network' but kasa can already do what you need :-)

but it can not, and neither can anything, work 'upstream' in this fashion with the vlan :-(

@Ricky666 
It is ok, initial message was not for you, but for talented TP-Link engineers.
Don't take it wrong, but I suggest you to be more active in Ubiquiti community - there you will have a chance to write 20 pages about their crappy software and your visions on technology, anyway they will not listen to you or will break whatever is still working.