Just recently I've purchased the R470T+ to combine my unreliable WISP broadband and a 4G LTE service.

I live in a rural area with no access to landline etc.

The WISP is a 10Mbps service supplied by a local company after 5 years it has started to become 'erratic' my AP is a Ubiquiti LM5 - I have no access to it except by a DHCP wired connection.

The 4G modem is a Huawei B535-235 with default settings, it's WAN port is 192.168.8.1 DHCP - it works well.
The TL-R470T+ is at static IP 192.168.0.1

After the TL-R470T+ is a Ubiquiti USG, at static IP 192.168.1.1 which 'splits' to 2 subnets, 192.168.1.0/24 and 192.168.2.0/24
These feed variuos managed switches and Unifi wireless AP's.

B535-235 4G LTE   > TL-R470T+ WAN1 Dynamic IP, showing 192.168.8.116 - which I assume the B535 gives to the TL-R470T+
LM5 WISP receiver > TL-R470T+ WAN2 Dynamic IP, showing 192.168.9.150 - which I assume the LM5 gives to the TL-R470T+
TL-R470T+ LAN port> USG WAN port > 192.168.1.0/24 and 192.168.2.0/24

The setup works well and as I have left 'Enable Application Optimized Routing' un-ticked, uses both connections to increase my connection speeds > 10Mbps
But as predicted causes problems with on-line banking due to mult-thread acess etc.

So I've tried to setup a static route, but are stumped by what to put as the 'next hop'

Any help would be appreciated.