Networking – Recv-Q is not empty for UDP sockets on Ubuntu 18.04


Since upgrading to Ubuntu 18.04 (already half a year), I still see that Recv-Q is never empty for many UDP sockets. The same picture shows DigitalOcean VPS when I upgraded it to Ubuntu 18.04. Ubuntu 16.04 and 17.10, which I have tested, are doing well.

These non-empty UDP receive queues result in UDP datagrams not being received on receipt or only delayed.

I just did it

sudo apt-get update
Sudo apt-get upgrade

but it did not help.

$ lsb_release -a

Distributor ID: Ubuntu
Description: Ubuntu 18.04.1 LTS
Publication: 18.04
Code name: Bionic

$ uname -a

Linux 4.15.0-39-generic # 42-Ubuntu SMP Tue 23.10. 15:48:01 UTC 2018 x86_64 x86_64 x86_64 GNU / Linux

$ netstat -lup

(Not all processes could be identified, no process information is displayed that is not owned by the company, you would need to be root to see all the information.)
Active Internet connections (server only)
Foreign address of the local address of Proto Recv-Q
State PID / program name
udp 4096 0 0.0.0.0:1900 0.0.0.0:*
udp 0 0 0.0.0.0:1901 0.0.0.0:* -
udp 0 0 0.0.0.0:42931 0.0.0.0:* -
udp 5120 0 localhost: 43804 0.0.0.0:* -
udp 5120 0 blade-HP-ProBook-: 44807 0.0.0.0:* -
udp 0 0 Blade-HP-ProBook-: 44926 0.0.0.0:* -
udp 0 0 localhost: 37844 0.0.0.0:* -
udp 42240 0 0.0.0.0:mdns 0.0.0.0:* -
udp 0 0 Blade HP ProBook: 46481 0.0.0.0:* -
udp 0 0 0.0.0.0:32410 0.0.0.0:* -
udp 8448 0 0.0.0.0:32412 0.0.0.0:* -
udp 0 0 0.0.0.0:32413 0.0.0.0:* -
udp 8448 0 0.0.0.0:32414 0.0.0.0:* -
udp 41472 0 localhost: domain 0.0.0.0:* -
udp 0 0 0.0.0.0:bootpc 0.0.0.0:* -
udp 18432 0 192.168.0.25:netbios-ns 0.0.0.0:* -
udp 0 0 blade-HP-Pro: netbios-ns 0.0.0.0:* -
udp 18432 0 0.0.0.0:netbios-ns 0.0.0.0:* -
udp 7680 0 192.168.0.2:netbios-dgm 0.0.0.0:* -
udp 0 0 Blade-HP-Pr: Netbios-dgm 0.0.0.0:* -
udp 7680 0 0.0.0.0:netbios-dgm 0.0.0.0:* -
udp 0 0 0.0.0.0:33097 0.0.0.0:* -
udp 0 0 0.0.0.0:ipp 0.0.0.0:* -
udp 5120 0 0.0.0.0:17500 0.0.0.0:* 2386 / Dropbox
udp 10240 0 0.0.0.0:17500 0.0.0.0:23 2386 / Dropbox
udp 0 0 0.0.0.0:50414 0.0.0.0:* -
udp6 49152 0 [::]: mdns               [::]: * -
udp6 0 0 [::]: 50237              [::]: * -   

I've been waiting for the problem to resolve, but it seems nobody else has this problem.
Can someone help me please?