Hi, 

I have two Vr600 v3 routers. The first (Master) is on the DSL Modem Router operation mode and connected to the landline adsl cable (IP: 192.168.1.1, DHCP: 192.168.1.2 - 192.168.1.199)

The second (slave) is on DSL Modem Router operation mode and connected to the master over an ethernet cat 6 cable (LAN-LAN connection), i assigned to it this ip: 192.168.1.199 i also disabled the DHCP on the slave router. Both master and slave have the same subnet mask: 255.255.255.0

Each one has its own SSID name. 

The issue is whenever I disconnect a device from the slave router and connect it to the master router, then reconnect it again to the slave router, the device wont get internet connection from the slave router, If i connected the same device again to the master router the device gets internet connection. 
(when the device is connected to the slave router and lost the internet connection I have to wait for 3 to 5 minutes to get internet again)

The issue is available on: 
Windows PC (all the PCs at home)
MAC OS (On MAC OS it's different: if the mac is connected to the master router then i connect it to the slave router it loses the internet connection, if i reconnect it back to the master router it doesn't get the internet connection back)
Android OS (Mobiles Phones) 

The issue is not available on: 
iOS 14.7 (iPhone 6s Plus)