link upload errors - ?

Hi guys.

I have something which I think I can say is peculiar & weird.
I monitor a net link, wireguard interface to be specific, 
about which 'monit' is not happy.
I see:
...
'wg0' 8 upload errors detected
'wg0' trying to restart
'wg0' stop: '/usr/bin/systemctl stop [email protected]'
'wg0' start: '/usr/bin/systemctl start [email protected]'
'wg0' download errors check succeeded
...

What are the errors 'monit' reports?
I watch the link and and link stays up, nothing seems wrong 
with it except 'monit' sees it as "failed"
In monit confg i have regular stuff I believe:

check network wg0 with interface wg0
   start program = "/usr/bin/systemctl start 
[email protected]"
   stop program  = "/usr/bin/systemctl stop 
[email protected]"
   if failed link then alert
   if 3 restarts within 20 cycles then unmonitor

What makes it weird - aside the fact that I cannot see link 
is down - is the fact that this wg0 link connects to two 
hosts which are too watched by 'monit', their wg0 ifaces 
naturally, and there on both those hosts monit is happy, no 
action needed.

all suggestion on how to troubleshoot this are very welcomed.
thanks, L.