Raspberry Pi local network problems. (Debian Stretch)
 

I have a 3b+ that I’m trying to connect. It’s connected to the home wireless router, wirelessly. I have the wlan0 (static) 192.168.1.5 with gateway and dns as local router(192.168.1.1). The eth0 is set to static as well(192.168.1.6) with no gateway or dns. The metric for preference is wlan0 first. I want to be able to VNC into the rpi (can do now) and from the rpi connect to devices on the eth0 network (2 solar inverters). When I have eth0 connected, I cannot access VNC or ping anything on the wireless network (using pi directly) but can access devices on the eth0 network. Connecting the eth0 to a hub the eth0 seems to turn off because no dhcp, even tho it’s been set static. Both wlan and eth have same syntax in dhcpd.conf. Wireless symbol at top of desktop says wlan is connected to correct network and has correct ip. Eth0 says expired even tho it shows ip.
My knowledge of Linux is very little. Can you please be kind and explain how I would go about fixing this and what is wrong in the first place. Thanks.

Why not just connect via the wlan interface? Having a second network interface assigned with an IP address in the same subnet can cause issues...
https://www.ni.com/en-nz/support/doc...ics--with.html

For a more definitive picture, please post back with output from