I have this issue intermittently. Sometimes I can play for hours (with a squad of 3 - 8) and experience no issues.
Other times I cannot play for the entire day, whether it be alone or with a group.
My character will become so desynced I cannot perform any action apart from moving. This includes vaulting (why is this server side?!), right clicking an item, changing weapon, opening doors etc.
As far as I can tell (after some pinging Day Z and Arma 3 servers) they will not accept a packet of a size greater than 1400 bytes. With that in mind I changed the MTU.
I actually had some success by changing the MTU. First I edited my DayZ profile (my docs\dayz other profiles\[char name].cfg) and added:
This didn't seem to work. After this I enforced an MTU of 1200 in my router settings and this seemed to work for a couple of days.
Perhaps this is a coincidence.
Also, I can play Arma 2 + 3 with little desync.