I also have this problem when using connect.securifi.com.
Honestly, I don't understand the selectable wireless modes as they're named on the local interface.
For example:
11NGHT20 (there's also 40, PLUS, MINUS, etc)
or
11ACVHT80
They're just a mashup of a description.
11 - 802.11 standard
N - Wireless N
G - Wireless G
AC - Wireless AC
HT - High-Throughput
VHT - Very High-Throughput
10/20/40/80 - Channel width (MHz)
PLUS and MINUS are tuners for the top and bottom halves of the channel spectrum, are are supposed to tune performance, but I've never noticed much of a difference between them and using just the standard 11NGHT40.
Here's a channel width breakdown for Wireless AC, you can find similar things for N:
Spatial Streams | 20 MHz | 40MHz | 80MHz |
1 | 86 Mbps | 200 Mbps | 433 Mbps |
2 | 173 Mbps | 400 Mbps | 866 Mbps |
3 | 288.9 Mbps | 600 Mbps | 1.3 Gbps |
Since the A+ has 3x3 MIMO, the AC connection tops out at 1.3 Gbps (using the 80MHz setting as shown in the table above, thus the 11ACVHT80 setting). This will also be limited by the card in your computer as well: for instance, mine only supports 2x2 MIMO so I can only utilize a max of 866 Mbps.