Model : TL-R480T+

Hardware Version : TL-R480T+ v7.0

Firmware Version : 1.1.0 Build 20150526 Rel.71825s

ISP : salt.(WAN1), sunrise (WAN2), swisscom(WAN3)

I have to following configuration:

On LAN Site 172.22.99.x Netzwork (Direct connected to a Firewall)
WAN 1 LTE Modem 1 (192.168.8.x)
WAN 2 LTE Modem 2 (192.168.1.x)
WAN 3 LTE Modem 3 (192.168.0.x)
All segment with mask 255.255.255.0

My Clients are behind the Firewall on the LAN site. Now i will configure all 3 LTE Modem from my client. But only the LTE Modem 192.168.8.1 on WAN1 i can.

I try with Policy Routing Destination 192.168.1.1-255 to WAN2, but not work.
What i forgott?