Set account name instead nickname:
addEventHandler('onPlayerLogin', root, function(_,account)
setPlayerName(source, getAccountName(account))
end)
Save account name on first server login and loading:
addEventHandler('onPlayerLogin', root, function(_,account)
local accName = getAccountData(account, 'savedName')
if not accName then
accName = getAccountName(account)
setAccountData(account, 'savedName', accName)
end
setPlayerName(source, accName)
end)