The OS is Win7 x64.
edit: I did not contact Lenovo. They typically don't support their drivers/software and I know the driver really came from Intel, who had a previous problem with SEP.
Please refer to information below , hopefully could be of some help:
1) Please try disable the power management option in the property of I218LM in device manager
2) Regarding the transferring of the file of several hundred MB or a couple GB then it'll copy about 10 MB then disconnect, does this same issue occur if you tried to transfer file lower than 100 MB, like if it will copy about 10 MB then disconnect?
3) What was the driver version for I218LM before that you encountered the SEP and sleep issue? Is the SEP version 12.1.5 as well?
4) Have you contacted Symantec support about this issue?
1. I have tried that before posting after finding online that the PM could cause this issue.
2. Sometimes it will copy small amounts, but it will eventually drop out. I've had it drop when only surfing the net.
3. This is a brand new (to us) laptop model (t450s). We haven't used any driver other than the latest from Lenovo (188.8.131.520). I tried the latest Intel driver package from 6/2/15 which installed v. 184.108.40.206, we are still experiencing the issue. I don't want to go back in revisions b/c we'll run into the problem with SEP and the card not working coming out of sleep mode that the latest revision fixed.
4. I have not; I plan on making calls today. I've been busy but have the time to look into it this week.
Sorry I haven't posted the resolution, I've been busy. We, Symantec and I, found this issue. Turns out as we've been upgrading our SEP server the firewall policy has not actually been upgrading along with it. There were a ton more rules that we didn't have in our policy. We deleted the old policy and created a new policy from the default. We now have all the rules and everything works. The only thing I can think of is that at some point there was a definition update to the firewall or something and that's when we started having issues. Just a guess b/c the server and network had been running fine up till a few weeks ago.
That was a weird one.