SEP deployment from console success rate is very less, what is could be the reason, please help is this normal,

Does all client are online ?

See below articles

Preparing Windows and Mac computers for remote deployment

Push install Symantec Endpoint Protection 12.1 clients using Remote Push

Post the SEP_INST.log and SIS_INST.log files from an affected client:

Required logs for troubleshooting failed Endpoint Protection 12.1 client installations

yes all clients are online, it is happening but very slow and less success rate. we have 0 days applied as well.

We just want to try only from SEPM console to deploy at present but it is happening but very slow and less success rate.

How is your bandwidth? How many clients?

Please post the logs affected client more troubleshooting

we are doing 20 system in a day, out of that 4 systems are upgrading in a day,

have you check restart the client ?

You can use autoupgrade feature for upgrading.

How to upgrade Symantec Endpoint Protection clients by using Auto-Upgrade

When you set it to 0 that may kill your bandwidth asit happens automatically, please verify.

Post the logs as well

what is maximum clients we can do at a time for upgrade

What is bandwidth we require actually for this

Is SEPM will restrict how many systems can download update at any particular time

There is no limit to the max amount of clients you can upgrade. It's what your network can handle...

Same goes for bandwidth. Whatever your network can handle..

You can limit bandwidth in 12.1.5 per the steps here:

Symantec Endpoint Protection Bandwidth Control for Client Communication

Is SEPM will restrict how many systems can download update at any particular time,

Ex: we have 20 system in group for upgrade but upgrded 4 systen withing 24hrs

Is there anything  have to advise for the slower

Here is Upgrade Schedule Calculation formula

Upgrade Schedule lets you control the time of the client computer upgrade.

- From, To:

• Specifies a range of time over which to install packages. If the From and To times match, the upgrades start immediately.

- Distribute upgrades over:

• Specifies the number of days or hours over which the packages can be distributed.
• The following formula calculates time:

• • (Package Size\Server Transfer Rate) * Number of Computers

    as

    MB / MB per second * Num = seconds

https://www-secure.symantec.com/connect/forums/sep-1214-mp1-agent-upgrade#comment-10345331

Not really. All clients within the group will get the upgrade. You can't only choose a specific amount. You're best off setting "x" amount of days for it to proceed with upgrade. You can also limit bandwidth per my link above.

please let us know what logs you need from client to check the issue