I'm seeing about 1.7% stale shares with Antminer L3+.  Ping time to us, us2, and generic addresses are around 28 ms, 66 ms, and 98 ms, respectively:

ping litecoinpool.org

Pinging litecoinpool.org [88.80.187.187] with 32 bytes of data:
Reply from 88.80.187.187: bytes=32 time=98ms TTL=48
Reply from 88.80.187.187: bytes=32 time=98ms TTL=48
Reply from 88.80.187.187: bytes=32 time=98ms TTL=48
Reply from 88.80.187.187: bytes=32 time=98ms TTL=48

Ping statistics for 88.80.187.187:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 98ms, Maximum = 98ms, Average = 98ms

ping us2.litecoinpool.org

Pinging us2.litecoinpool.org [104.236.136.96] with 32 bytes of data:
Reply from 104.236.136.96: bytes=32 time=66ms TTL=43
Reply from 104.236.136.96: bytes=32 time=66ms TTL=43
Reply from 104.236.136.96: bytes=32 time=66ms TTL=43
Reply from 104.236.136.96: bytes=32 time=67ms TTL=43

Ping statistics for 104.236.136.96:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 66ms, Maximum = 67ms, Average = 66ms

ping us.litecoinpool.org

Pinging us.litecoinpool.org [104.236.57.24] with 32 bytes of data:
Reply from 104.236.57.24: bytes=32 time=28ms TTL=47
Reply from 104.236.57.24: bytes=32 time=28ms TTL=47
Reply from 104.236.57.24: bytes=32 time=27ms TTL=47
Reply from 104.236.57.24: bytes=32 time=26ms TTL=47

Ping statistics for 104.236.57.24:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 26ms, Maximum = 28ms, Average = 27ms

I recently upgraded my cable modem and upgraded from CAT 5/6 to CAT 8 cabling and reduced the number of internal switches in the path from the miners to the modem.  So now I'm at a loss as to how to further reduce the stale shares.  Any suggestions?