This is not really an error, it's just an info message saying that the system cannot put the socket connection into time-wait state (buffer is full) and the socket will be closed. The reason for setting this limit is to resist simple DoS attacks.

[cc lang='bash']
\$ dmesg | tail
[660665.919463] TCP: time wait bucket table overflow
[660665.919694] TCP: time wait bucket table overflow
[660665.919791] TCP: time wait bucket table overflow
[660665.919815] TCP: time wait bucket table overflow
[660665.920378] TCP: time wait bucket table overflow
[660665.921349] TCP: time wait bucket table overflow
[660665.921503] TCP: time wait bucket table overflow
[660665.922086] TCP: time wait bucket table overflow
[660665.928561] TCP: time wait bucket table overflow
[660665.928601] TCP: time wait bucket table overflow

\$ sysctl net.ipv4.tcp_fin_timeout
net.ipv4.tcp_fin_timeout = 5 # this is already lowered from the default 60
\$ sysctl net.ipv4.tcp_max_tw_buckets
net.ipv4.tcp_max_tw_buckets = 262144 # this needs to be increased
[/cc]