Can anybody please explain what this means in the wireless stats for AP client: 2S/SGI or 1S/SGI?
Many thanks.

Can anybody please explain what this means in the wireless stats for AP client: 2S/SGI or 1S/SGI?
Many thanks.

2S is short of 2 stream it is mean using both antenna chain.
1S short of 1 stream using one antenna chain.
SGI is short guard interval.
From Wikipedia
The standard symbol guard interval used in 802.11 OFDM is 0.8 μs. To increase data rate, 802.11n added optional support for a 0.4 μs guard interval. This provides an 11% increase in data rate.
Perfect, thanks.