Thank you.If you just open up a command prompt and ping the switch, it should stay around 1-2ms until libreNMS's scheduled polling happens
My concern started when I observed the Gateway monitoring on OPNsense. (OK, my fault. What you do not know, does not make you concerned about.) Significant different values to the gateway on DSL modem than to directly connected switch. On OPNsense side both same NICs are same type and both directly connected via copper without LAGG and without VLAN in between. (see below)
Ping from Windows machine directly connected via fiber shows similar behavior. (see below)
When I will find time, I will check if there is any relation to other activities. In every case there is no load on my switch. This device is oversized for it purpose on mainly is doing nothing else than creating noise, generating heat and increasing the electricity bill.
OPNsense monitor
PING to switch