What is the initial TCP Receive Window size in Android? This may be pretty similar to the question here, however, I think it was either in the wrong place, or it wasn't clear enough, so it hasn't got to the right audience. Thus, I have re-formulated it here:
Intro:
The TCP Receive Window is the size of the buffer on the receiving end of a TCP connection. According to (RFC7323 - Section-1.1) the TCP standard has a 16-bit field to denote the size (2^16 = 65,536 Bytes max). However, this has been seen to limit performance in high latency networks (RFC7323). Thus, a field has been included in the TCP options/extensions called the &quot;Window Scale&quot; (RFC7323 - Section-2) in order to improve performance by increasing the Receive Window size by multiplying it by a scaling factor, thus Scaling Factor = 2 ^ Window Scaling Factor Value. So in essence the TCP Receive Window Size = TCP Receive Window Value * (2 ^ Window Scaling Factor Value) (Haven't fully understood how the scaling factor actually works, so this might not be entirely accurate).
Question:
The essence of this question is, according to RFC7323 - Section 2.1, it seems that the TCP stack implemented in different operating systems has a different default initial value. What is the default initial TCP Receive Window size in Android? Has it changed over the different versions?
References:
RFC 7323 - https://tools.ietf.org/html/rfc7323
I can answer you about TCP WINDOW SIZE and TCP WINDOWSCALE fields as they appear in the TCP header.

Initial TCP Window Size should be 0x3908 = 14600, at least it is what I found so far using several versions.

(On most Linux distro I've used it is exactly the double 0x7210 = 29200.)

Window Scale has different values depending on the version, older set it to 6, newer set it to 8, at least for what I experienced so far.

You can check both values with this app:
https://play.google.com/store/apps/details?id=be.ac.ulg.mobiletracebox 
It will show you them in the first line 

0: youraddress ... TCP::Window (0xXXXX) ... TCP::WindowScale (0xXX)

Values are hexadecimal. 

For Window Size use regular Syn probe.

For Window Scale use Window Scale probe.

(If no value is shown for Window, it should be the max (0xffff=65535). If your device is rooted you should set mode to server based.)

PS
I don't know if talking about an app is OK here, if not I'm more than willing to edit my comment.