MWAN3 renewing DHCP-adresses

I'm using OpenWrt on a D-Link DWR-921 C1 router and its built-in modem WWAN for acces to lte; the WAN-Port is connected to a Scout WiFi-Router which I want to connect to different access-points using its bridge-mode. I've installed MWAN3 for failover (if Wifi goes down and only lte is available) and all works fine. But after changing the WLAN-AP the WAN-Interface stays offline and shows the old IP-adresses. To get the new adresses I have to restart the WAN-Interface manually and then all is ok. Is it possible to update the adresses without restarting the interface manually?
Many thanks for your answer!