Hello,
I could not find other way to report bug I found with default configuration on ESET Internet Security (Windows 10),
straight after activation ESET breaks PMTUD, any packets with don't fragment flag set are being randomly modified and flag cleared so it allows IP fragmentation as a result. I have also noticed that traceroute is broken always pinging destination on first hop (this is due to TTL field being reset to default 128). I don't think it's correct behaviour unless I don't understand something.
Once switched from Internet Security to NOD32 I don't have this problem and PMTUD & traceroute behave as they should.
I can provide more information if needed.
My product version is 17.1.9.0
OS: Win10 64bit