Im thinking could it be that you for whatever reason are running out of conntrack table space?
One way if you dont use the firewall settings is to disable conntrack (trying to figure out how to do that in VyOS 1.4) the other is to tweak the timers to something like so (dont just copy the values, depends on how much RAM you got etc but you get a hint of which settings to dig into further):
system {
conntrack {
expect-table-size 10485760
hash-size 10485760
table-size 10485760
timeout {
icmp 10
other 600
tcp {
close 10
close-wait 30
established 600
fin-wait 30
last-ack 30
syn-recv 30
syn-sent 30
time-wait 30
}
udp {
other 600
stream 600
}
}
}
option {
performance throughput
reboot-on-panic
startup-beep
}
}
Ref: Bgpd 10Gbps nf_conntrack: table full, dropping packet - #4 by sidnei