Advanced networking troubleshooting

I'm using an HP Envy m6-1205dx laptop with onboard Realtek PCIe GBE family controller network adapter, a netgear WNDR4300 wireless router and a Motorola DOCSIS 3.0 cable modem. I'm connected via 350mhz CAT5e cable to the router and I'm connected solidly at a 1Gbps rate. The problem though is my throughput speeds are poor. Comcast, Centurylink and Speednet tests all show a 28mbps connection down and about 4.5mbps up. That would be ok as my advertised speed for my tier is 25mbps and 4mbps but the reality is I'm not getting that speed in real world application regardless of where I download from or what size files are being downloaded. About the fastest I've been able to download a file at is 513kbps which of course is only 4.13 mbps, or just about right on to what M-labs is reporting. The NDT from M-labs is showing I only have a 4.4mbps download and a 4.3mbps upload. It's also saying something about only having a 32kb buffer which limits throughput to 4.56mbps. I'm unsure what this is all about as my network adapter shows a 512 receive buffer and a 128 transmit buffer. Maybe not the same buffer M-labs is talking about? I thought maybe it was a port setting issue however Windows 8.1 has no communications port settings in device manager even if you enable hidden devices. Below is the M-labs NDT report and my Google traceroute. I'm pretty technically astute but I'm a bit weak when it comes to the advanced networking side of things so if somebody in the know can take a look at this and tell me what is likely holding me back I'd really appreciated it. Thanks.

Tracing route to google.com [74.125.225.166]
over a maximum of 30 hops:

1 <1 ms <1 ms <1 ms 192.168.1.1
2 8 ms 8 ms 10 ms 71.196.250.1
3 8 ms 8 ms 8 ms te-7-7-ur02.pueblo.co.denver.comcast.net [68.85.
220.229]
4 34 ms 34 ms 34 ms xe-14-1-0-0-ar01.aurora.co.denver.comcast.net [6
8.86.179.45]
5 35 ms 36 ms 37 ms he-3-10-0-0-cr01.denver.co.ibone.comcast.net [68
.86.92.25]
6 35 ms 34 ms 34 ms xe-2-1-2-0-pe01.910fifteenth.co.ibone.comcast.ne
t [68.86.82.22]
7 35 ms 35 ms 34 ms as15169-1-c.910fifteenth.co.ibone.comcast.net [2
3.30.206.106]
8 34 ms 35 ms 34 ms 72.14.234.59
9 35 ms 34 ms 35 ms 209.85.251.9
10 35 ms 35 ms 35 ms den03s05-in-f6.1e100.net [74.125.225.166]


NDT test run towards M-Lab server
ndt.iupui.mlab2.dfw01.measurement-lab.org

RTT between client and M-Lab server
52 ms

DOWNLOAD SPEED
4.4 Mbps

UPLOAD SPEED
4.3 Mbps



Client System Details
OS data:: Windows 8.1, Architecture: x86
Flash Info: Version = WIN 14,0,0,145
The slowest link in the end-to-end path is a
a 622 Mbps OC-12 subnet
This connection is receiver limited 93.65% of the time
This connection is network limited 3.22% of the time
622 Mbps OC-12 link found.
Link set to Full Duplex mode
No network congestion discovered.
Good network cable(s) found
Normal duplex operation found.
Web100 reports the Round trip time = 54.83ms
the Packet size = 1460bytes
No packet loss was observed.
C2S throughput test: Packet queuing detected: 7.55%
S2C throughput test: Packet queuing detected: 7.55%
Web100 reports TCP negotiated the optional Performance Settings to:
RFC 2018 Selective Acknowledgement:
ON
RFC 896 Nagle Algorithm:
ON
RFC 3168 Explicit Congestion Notification:
OFF
RFC 1323 Time Stamping:
OFF
RFC 1323 Window Scaling:
OFF
The theoretical network limit is 20313.53 Mbps
The NDT server has a 49.05 KByte buffer which limits the throughput to 13.98 Mbps
Your PC/Workstation has a 32.00 KByte buffer which limits the throughput to 4.56 Mbps
The network based flow control limits the throughput to 5.28 Mbps
Client Data reports link is OC-12
Client Acks report link is OC-12
Server Data reports link is Ethernet
Server Acks report link is Ethernet
=== Results sent by the server ===
CurMSS: 1460
X_Rcvbuf: 87380
X_Sndbuf: 100464
AckPktsOut: 0
BytesRetrans: 0
CongAvoid: 0
CongestionOverCount: 0
CongestionSignals: 0
CountRTT: 1951
CurCwnd: 37960
CurRTO: 255
CurRwinRcvd: 32768
CurRwinSent: 5888
CurSsthresh: 2147483647
DSACKDups: 0
DataBytesIn: 0
DataBytesOut: 5848836
DataPktsIn: 0
DataPktsOut: 3954
DupAcksIn: 0
ECNEnabled: 0
FastRetran: 0
MaxCwnd: 37960
MaxMSS: 1460
MaxRTO: 258
MaxRTT: 73
MaxRwinRcvd: 32768
MaxRwinSent: 5888
MaxSsthresh: 0
MinMSS: 1460
MinRTO: 254
MinRTT: 52
MinRwinRcvd: 32768
MinRwinSent: 5840
NagleEnabled: 1
OtherReductions: 0
PktsIn: 1951
PktsOut: 3954
PktsRetrans: 0
RcvWinScale: 7
SACKEnabled: 3
SACKsRcvd: 0
SendStall: 0
SlowStart: 23
SampleRTT: 55
SmoothedRTT: 55
SndWinScale: 0
SndLimTimeRwin: 9673078
SndLimTimeCwnd: 332177
SndLimTimeSender: 323954
SndLimTransRwin: 1
SndLimTransCwnd: 6
SndLimTransSender: 6
SndLimBytesRwin: 5757200
SndLimBytesCwnd: 42920
SndLimBytesSender: 48716
SubsequentTimeouts: 0
SumRTT: 106983
Timeouts: 0
TimestampsEnabled: 0
WinScaleRcvd: 0
WinScaleSent: 7
DupAcksOut: 0
StartTimeUsec: 50831
Duration: 10332016
c2sData: 6
c2sAck: 6
s2cData: 3
s2cAck: 3
half_duplex: 0
link: 10
congestion: 0
bad_cable: 0
mismatch: 0
spd: 4.53
bw: 20313.53
loss: 0.000000000
avgrtt: 54.83
waitsec: 0.00
timesec: 10.00
order: 0.0000
rwintime: 0.9365
sendtime: 0.0314
cwndtime: 0.0322
rwin: 0.2500
swin: 0.7665
cwin: 0.2896
rttsec: 0.054835
Sndbuf: 100464
aspd: 0.00000
CWND-Limited: -0.03
minCWNDpeak: -1
maxCWNDpeak: -1
CWNDpeaks: -1

Client System Details
OS data:: Windows 8.1, Architecture: x86
Flash Info: Version = WIN 14,0,0,145
The slowest link in the end-to-end path is a
a 622 Mbps OC-12 subnet
This connection is receiver limited 78.60% of the time
This connection is network limited 18.13% of the time
622 Mbps OC-12 link found.
Link set to Full Duplex mode
No network congestion discovered.
Good network cable(s) found
Normal duplex operation found.
Web100 reports the Round trip time = 55.35ms
the Packet size = 1460bytes
1 packets retransmitted
21 duplicate acks received
21 SACK blocks received
The connection was idle 0.00 seconds (0.00% of the time)
C2S throughput test: Packet queuing detected: 7.23%
S2C throughput test: Packet queuing detected: 7.23%
Web100 reports TCP negotiated the optional Performance Settings to:
RFC 2018 Selective Acknowledgement:
ON
RFC 896 Nagle Algorithm:
ON
RFC 3168 Explicit Congestion Notification:
OFF
RFC 1323 Time Stamping:
OFF
RFC 1323 Window Scaling:
OFF
The theoretical network limit is 12.29 Mbps
The NDT server has a 49.05 KByte buffer which limits the throughput to 13.85 Mbps
Your PC/Workstation has a 32.00 KByte buffer which limits the throughput to 4.52 Mbps
The network based flow control limits the throughput to 5.23 Mbps
Client Data reports link is OC-12
Client Acks report link is OC-12
Server Data reports link is Ethernet
Server Acks report link is Ethernet
=== Results sent by the server ===
CurMSS: 1460
X_Rcvbuf: 87380
X_Sndbuf: 100464
AckPktsOut: 0
BytesRetrans: 1460
CongAvoid: 272
CongestionOverCount: 0
CongestionSignals: 1
CountRTT: 1834
CurCwnd: 37960
CurRTO: 255
CurRwinRcvd: 32768
CurRwinSent: 5888
CurSsthresh: 16060
DSACKDups: 0
DataBytesIn: 0
DataBytesOut: 5520500
DataPktsIn: 0
DataPktsOut: 3731
DupAcksIn: 21
ECNEnabled: 0
FastRetran: 1
MaxCwnd: 37960
MaxMSS: 1460
MaxRTO: 264
MaxRTT: 88
MaxRwinRcvd: 32768
MaxRwinSent: 5888
MaxSsthresh: 16060
MinMSS: 1460
MinRTO: 253
MinRTT: 52
MinRwinRcvd: 32768
MinRwinSent: 5840
NagleEnabled: 1
OtherReductions: 2
PktsIn: 1856
PktsOut: 3731
PktsRetrans: 1
RcvWinScale: 7
SACKEnabled: 3
SACKsRcvd: 21
SendStall: 0
SlowStart: 33
SampleRTT: 55
SmoothedRTT: 55
SndWinScale: 0
SndLimTimeRwin: 8126871
SndLimTimeCwnd: 1874103
SndLimTimeSender: 338161
SndLimTransRwin: 3
SndLimTransCwnd: 7
SndLimTransSender: 5
SndLimBytesRwin: 4798160
SndLimBytesCwnd: 697080
SndLimBytesSender: 25260
SubsequentTimeouts: 0
SumRTT: 101503
Timeouts: 0
TimestampsEnabled: 0
WinScaleRcvd: 0
WinScaleSent: 7
DupAcksOut: 0
StartTimeUsec: 472806
Duration: 10340094
c2sData: 6
c2sAck: 6
s2cData: 3
s2cAck: 3
half_duplex: 0
link: 10
congestion: 0
bad_cable: 0
mismatch: 0
spd: 4.53
bw: 20313.53
loss: 0.000000000
avgrtt: 54.83
waitsec: 0.00
timesec: 10.00
order: 0.0000
rwintime: 0.9365
sendtime: 0.0314
cwndtime: 0.0322
rwin: 0.2500
swin: 0.7665
cwin: 0.2896
rttsec: 0.054835
Sndbuf: 100464
aspd: 0.00000
CWND-Limited: -0.03
minCWNDpeak: -1
maxCWNDpeak: -1
CWNDpeaks: -1
c2sData: 6
c2sAck: 6
s2cData: 3
s2cAck: 3
half_duplex: 0
link: 10
congestion: 0
bad_cable: 0
mismatch: 0
spd: 4.53
bw: 20313.53
loss: 0.000000000
avgrtt: 54.83
waitsec: 0.00
timesec: 10.00
order: 0.0000
rwintime: 0.9365
sendtime: 0.0314
cwndtime: 0.0322
rwin: 0.2500
swin: 0.7665
cwin: 0.2896
rttsec: 0.054835
Sndbuf: 100464
aspd: 0.00000
CWND-Limited: -0.03
minCWNDpeak: -1
maxCWNDpeak: -1
CWNDpeaks: -1
c2sData: 6
c2sAck: 6
s2cData: 3
s2cAck: 3
half_duplex: 0
link: 10
congestion: 0
bad_cable: 0
mismatch: 0
spd: 4.27
bw: 12.29
loss: 0.000268025
avgrtt: 55.35
waitsec: 0.00 I can provide the full report if needed.
timesec: 10.00
order: 0.0113
rwintime: 0.7860
sendtime: 0.0327
cwndtime: 0.1813
rwin: 0.2500
swin: 0.7665
cwin: 0.2896
rttsec: 0.055345
Sndbuf: 100464
aspd: 0.00000
CWND-Limited: -0.03
minCWNDpeak: 2920
maxCWNDpeak: 37960
CWNDpeaks: 1