Router sees network connections, but can't ping router

Router sees network connections (enp8s0 & enp9s0), but can’t ping router. Route table looks like: UG 0 0 0 enp8s0 UG 0 0 0 enp9s0 U 0 0 0 enp8s0 U 0 0 0 enp9s0

Router at, seeing (enp8s0) and (enp9s0).
DHCP is disabled for both connections.
NetworkManager in control.
I swear the connections are configured correctly.

What should i look for?

Hello @darksky and welcome.

You have two network interfaces on the same subnet, what do you want to achieve?
However, the router should reply to ping requests. Are you sure that the router isn’t configured to drop ping requests (a firewall on the router or the like)?
Out of curiosity could you show the result of this command?
ip route

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There are over a dozen devices connected to the router, all functioning normally. Other computers can ping the router and the external net. It’s not the router refusing to answer pings.

Try restarting the router and switch.
Check the IEEE 802.1Q and IEEE 802.1X settings on the router and switch.
If the issue persists, replace the cable and use a different port on the switch.
Check if you can capture any traffic with tcpdump on Fedora:

sudo tcpdump -evnni any

I think I figured it out. First, I was connecting to the router through a little 5-port edge router - I am now wired around it to one of the ethernet interfaces. Second, NetworkManager ‘selected’ enp8s0 as the active/default connection (you can tell that because outgoing pings reveal which ip address is initiating the ping), but the router was now showing active, thus causing a mismatch between active on the machine and recognized by the router, thereby making router and external pings fail. When I moved the LAN cable from one external connector to the other, pings started working. It’s likely that NetworkManager selecting the non-wired port is a bug, a design oversight at least.

Sometimes, it just takes having to explain yourself rationally to a third party to reveal errors and misconceptions in the analytical thought process. Thanks for being my networking muse.