>> >> Maybe run a ping to a destination which you are having problems >> >> with, then reproduce the problem (with the network idle >> >> otherwise). You should see ping packets dropped only then. >> >> >> >> You can also ping with increasing packet sizes (see ping --help) >> >> and see when the packet becomes too big for path MTU. But instead >> >> lowering your MTU then, you should allow icmp-fragmentation-needed >> >> come through reliably. Lowering MTU only makes sense to stop >> >> overly fragmentation in the first place and optimize for a >> >> specific packet path (like traffic through one or multiple VPN >> >> tunnels) where fragmentation would otherwise increase latency a >> >> lot, or where icmp-frag-needed does not correctly work. >> > >> > >> > I'll try pinging today once the issue pops up. >> >> >> I'm seeing the issue again as usual but ping response times come back >> normal at about 50ms. I'll keep trying. > > Not sure if this came after or before switching your router to modem > mode... But if it happened before and is solved now, your router really > doesn't well with icmp packets or has problems with mss clamping / pmtu.
I did not try pinging before switching the device from router to modem. BTW, I read that setting CLAMPMSS=Yes in shorewall.conf is a necessity when using PPPoE but my connection is working fine without that setting. Should I set it anyway? - Grant
