I just saw this one today. Only one host, failed probe for "routeros management" and the RouterOS connection also Dude timeouts (so links etc also don't work).
Dude is running 6.49 (hEX S) and remote monitored device is running 7.9.1 (NetPower 16p). I can connect to same device with winbox (via zerotier) no problem. No firewall issue since same network as Dude server can also access via winbox. But the Dude server reports the problem as "unknown dst device (20326) (6)" in the probes for monitored device.
Not sure what's going on. Seems to be only the one device as there are dozens of RouterOS devices monitored, with mix of various V7 versions and V6 stable that work with Dude's RouterOS monitoring stuff. And another ROS router with 7.9.1 works fine. The NetPower 16p that get this error was running 7.7 which is what it was running when I tried to add this new router to Dude – upgrade to 7.9.1 to see if fixes but same error as 7.7.
Anyone else seen this?