Significant Dropped Packets on WG interface

[Mike O'Connor]

Hi All

For the last few weeks my Wireguard link which I use to as my default
gateway has been having issues with TCP connections stalling.

I've been trying to work out what is wrong. I just noticed that the
Wireguard link has dropped packets at both ends.

wg-p2p    Link encap:UNSPEC  HWaddr
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:104.127.123.10  P-t-P:103.127.123.10 
Mask:255.255.255.248
          inet6 addr: 2506:c500:ff4:1::ab/64 Scope:Global
          inet6 addr: fe80::e6/64 Scope:Link
          UP POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
          RX packets:141849 errors:0 dropped:5915 overruns:0 frame:0
          TX packets:141626 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:33771496 (33.7 MB)  TX bytes:14348632 (14.3 MB)

wg-p2p    Link encap:UNSPEC  HWaddr
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:104.127.123.9  P-t-P:103.127.123.9  Mask:255.255.255.248
          inet6 addr: 2506:c500:ff4:1::aa/64 Scope:Global
          inet6 addr: fe80::dc/64 Scope:Link
          UP POINTOPOINT RUNNING NOARP  MTU:1500  Metric:1
          RX packets:663287 errors:1 dropped:1433 overruns:0 frame:1
          TX packets:1023948 errors:594 dropped:13 overruns:0 carrier:0
          collisions:0 txqueuelen:1
          RX bytes:110192140 (110.1 MB)  TX bytes:872273836 (872.2 MB)

Note the above is after a reboot of both end points (about 4 mins)

One end is running a 4.4.0 kernel

ii  wireguard                            
1.0.20200510-1~16.04                            all          fast,
modern, secure kernel VPN tunnel (metapackage)
ii  wireguard-dkms                       
1.0.20200429-2~16.04                            all          fast,
modern, secure kernel VPN tunnel (DKMS version)
ii  wireguard-tools                      
1.0.20200510-1~16.04                            i386         fast,
modern, secure kernel VPN tunnel (userland utilities)

The other is

ii  wireguard                                
1.0.20200319-1ubuntu1~14.04                          all          fast,
modern, secure kernel VPN tunnel (metapackage)
ii  wireguard-dkms                           
1.0.20200429-1~14.04                                 all          fast,
modern, secure kernel VPN tunnel (DKMS version)
ii  wireguard-tools                          
1.0.20200319-1ubuntu1~14.04                          amd64        fast,
modern, secure kernel VPN tunnel (userland utilities)

I was thinking of rebuilding the ubuntu 14.04 to a 16.04 (18.04 uses
netplan and can be a real pain to setup)


I've done my best to check the underlying Internet and I do not think
packets are be dropped in general or between the two end points.

How do I tell why the packets have been dropped ?

What do I need to look at to try to fix this ?


Thanks

Mike