Hi,
In RV345 Router, precedence 1 defines the primary link (for failover) and precedence 2 is the secondary link. In your case WAN1 is the primary link, so all the Internet traffic should be forwarded via that primarily. Once WAN1 goes down that time traffic will get diverted to WAN2.
You can check the WAN link UP and DOWN status on the log (make sure log settings are enable on the RV345 router), that indicates the physical connectivity status though. If the system time is updated properly then you can at least get an idea when the traffic was diverted to the other WAN link.
Alternatively, you can use the traceroute option in your system once you face the slow Internet connectivity issue as you have mentioned that WAN 2 having slow Internet connectivity. In case the WAN 1 link is down then WAN 2 gateway IP should reflect on the traceroute path after the LAN IP of the RV345 Router.
You may use the ‘Remote Host’ option with DNS IP you are using for WAN interface for ‘Detect Destination’ parameter under ‘Network Service Detection’ for better switchover between WAN interfaces in case of link failure. You may keep the default values for ‘Retry Count’ and ‘Retry Timeout’.
Regarding your secondary query, even though the option is not available to bind the physical LAN port to a specific WAN port directly. However, you can use the ‘Policy Based Routing’ option in RV345 router to divert the Internet traffic of a specific source IP (from LAN) via a specific WAN interface. In your case you can use WAN2 for stable connectivity. Alternatively, you may use ‘Static NAT’ option provided you have a free IP available on that specific WAN interface.
