DHCP Helper Problem

[kan3]

Hi, 

I have a 80D, with v5.4.4. 

Port1 is the transfer network with the box from my provider. In this network, are also my wireless equipment. Call it 192.168.178.0/24. 

Port2-4 are a Software Switch with a DHCP-Server (192.168.1.0/24). Now I want to connect the wireless clients from Port1 to the Software Switch.  So I configure a DHCP Helper Adress to Port1 with Adress 192.168.1.1. 

But the clients doesnt become a ipv4 adress. The debugging told me: 

2017-03-29 17:15:43 Relay client interface: port1 2017-03-29 17:15:43 get_server_intf( 192.168.1.1, 0x4821e90) 2017-03-29 17:15:43 found route to 192.168.1.1 via 192.168.1.1 if(8)/root 2017-03-29 17:15:43 unable to locate suitable server interface for relay server 192.168.1.1

But why? These is one of the foritgate ips.