Hi TPG I'm still waiting on a response to the below discussion. In simple form Im experiencing around 15-20ms extra ping latency on Wifi than on direct ethernet connection to the Sagemcom Modem. Also My current Sagemcom 5866t firmware version: SGJy10021E
Is there a newer version?
Please check this previous post for extensive discussion and tests performed:
The modem/router has the latest firmware available.
Ping on a WiFi connection might get higher depending on the interference that's affecting the signal.
Try to disable the band steering on the modem interface and change the WiFi channel to help improve your home network.