With pfctl you can check whether TCP window scaling is being used
Code:
# pfctl -vvss
all tcp 192.168.222.10:22 <- 192.168.222.20:32167 ESTABLISHED:ESTABLISHED
[1530147851 + 65487] wscale 0 [761161648 + 17376] wscale 0
age 00:06:59, expires in 24:00:00, 621:1038 pkts, 38500:213184 bytes, rule 22
id: 8990c04a75d43300 creatorid: 9f30c773
So in this SSH connection from my desktop 192.*20 to my router 192.*10 both communication endpoints negotiated a window scaling factor of 0, so none