Is that bad? Should I be worried?
No, please don't worry about it.
From my "poking about", starting with the destination IPv4 address that you showed, it is clear that someone very local to you (if it wasn't you), using a device connected to your LAN, had performed a speed test to an Ookla server based in Preston.
It is unfortunate that your modem/router sees the (legitimate) traffic and classifies it as a "Ping of Death", thus ensuring that one (or more) entry(ies) are logged.
I see a similar effect when I am connected to an IRC server. My ZyXEL VMG1312-B10A logs it as "SYN Flooding" and so I have become accustomed to seeing the warnings when I review the logfile, daily.
A four word summary:
You are not alone.