VLAN settings on mikrotike?

Question

Mikrotik

There is a Mikrotik router, its local network is in the factory range 192.168.88.1/24. The Internet comes to the sfp port via optics.
The second local network 172.20.15.1/24 comes to port 8.
I sketched an approximate scheme:

In the second local network there is no dhcp server, and no gateway (router). There are a number of devices there, all devices have static IPs set and they interact with each other.
The task is to make a separate vlan for the 8th port, or if you offer another option, you can do it without vlan.
It is necessary for me that devices from the second network do not receive addresses via dhcp from the local network of Mikrotik, if suddenly there is a device on the second network without an assigned static address. But at the same time, so that the devices from the second network are available when accessing them from the first Mikrotik local network. And also that Mikrotik would give the Internet, in addition to its local network, also a second, neighboring network on port 8. And it was also possible to carry out forwarding from a white, static external address on the sfp port to certain devices on the second network.
I tried the following according to the manuals from the network:
1. Through winbox in Interfaces -VLAN, create a VLAN with the name vlan50 and specify VLAN ID: 50, and in Interface: 8 mirotik port (ether8-slave-local). All other parameters of the created vlan left by default.
2. Further in IP - Addressess I added the range: By specifying address: 172.20.15.1/24 , Network: 172.20.15.0 , Interface: vlan50
3. Further in IP - FireWall - NAT I added the parvilo Chain: srcnat , Src. Address: 172.20.15.0/24 , which, according to the manual, should allow clients to connect to the network.
But it did not give the desired result... Devices from the second network are not visible from the local network of Mikrotik. And also port forwarding does not work on devices from the second network ...

Answer 1

vlan is not needed here, just set it to local_bridge dhcp, remove port 8 from the bridge, from the slave mode if there is one, then just hang up the IP address for the second local network on port 8 and that's it. vlan is configured not in the interface, you can configure the vlan port in the interface if you have tagged traffic coming from port 8.

Answer 2

I'm not sure, but it seems that this is not possible, since VLAN is a network within a network, that is, first a link must be set at the tcp IP level and you must get an IP address and after that a virtual subnet with identifier 50 is raised. and so that this port does not issue address, take it off the bridge, assign it a separate address and address space. and forward it through nat and firewall (if you need Internet access).
I'm sorry if I didn't answer properly, maybe I didn't fully understand you.