Tacert Fail And Site Is Not Displayed On Certain Networks

I have a server with serverboost.nl and my site is not reachable via some networks. We have done a both way tracert and it fails after few steps. I am not sure how many networks give this error but I have already received few complaints from regular visitors to the site.

1. Who/ what networks should I contact to resolve this issue? I ave already asked ServerBoost.nl and they said TRACERT fails at Cogent network.

2.Cogent replied saying the following
"Thank you for the trace example. What you were seeing was the 1st and last hop on the Cogent network mpd01.iad01. The very next hop then transfers over to the Savvis network. I have completed a successfully trace to the destination.

mpd01.iad01#trace
Target IP address: "MySiteIP"
Tracing the route to "MySiteIP"

1 savvis.iad01.atlas.cogentco.com (154.54.12.26) 0 msec <----- 1st hop of Savvis's network
ber1-ge-7-43.virginiaequinix.savvis.net (208.173.10.181) 0msec
ber1-ge-7-39.virginiaequinix.savvis.net (208.173.52.105) 0msec
2 cr1-tengig0-7-2-0.washington.savvis.net (204.70.197.242) [AS 3561] 0 msec 4 msec 0 msec
3 dcr2-so-0-0-0.amsterdamamx.savvis.net (204.70.194.122) [AS 3561] 96 msec 96 msec 100 msec
4 acr2-so-0-0-0.Amsterdamamx.savvis.net (204.70.193.149) [AS 3561] 96 msec 96 msec 96 msec
5 so-0-1-0.br3.ams.we-dare.net (208.174.49.170) [AS 3561] 100 msec 100 msec 96 msec
6 ge-1-1-0.br1.ams.we-dare.net (84.244.188.249) [AS 20495] 96 msec 96 msec 96 msec
7 ge-1-1-0.cr1.rtd.we-dare.net (217.148.164.3) [AS 20495] 100 msec 104 msec 104 msec
8 "MySiteIP" 100 msec 100 msec 96 msec
mpd01.iad01#

Thank you,
Kenneth Abernethy
Customer Support Engineer"

3. TRACERT from Visitor to My Site and vise versa

Tracing route to MySite.com ["MySiteIP"] (from client IP "ClientIP")
over a maximum of 30 hops:
1 1 ms 1 ms 2 ms 192.168.1.1
2 9 ms 9 ms 9 ms 10.35.180.1
3 10 ms 7 ms 10 ms vl-201.gw03.ktgc.phub.net.cable.rogers.com [66.185.90.49]
4 22 ms 7 ms 7 ms gi-3-0.gw01.ktgc.phub.net.cable.rogers.com [66.185.81.121]
5 15 ms 13 ms 14 ms 64.71.241.93
6 25 ms 27 ms 27 ms 69.63.248.42
7 46 ms 74 ms 179 ms te1-5.mpd01.iad01.atlas.cogentco.com [154.54.12.89]
8 * * * Request timed out.
9 * * * Request timed out.
10 * * * Request timed out.
11 * * * Request timed out.
12 * * * Request timed out.
13 * * * Request timed out.
14 * * * Request timed out.
15 * * * Request timed out.
16 * * * Request timed out.
17 * * * Request timed out.
18 * * * Request timed out.
19 * * * Request timed out.
20 * * * Request timed out.
21 * * * Request timed out.
22 * * * Request timed out.
23 * * * Request timed out.
24 * * * Request timed out.
25 * * * Request timed out.
26 * * * Request timed out.
27 * * * Request timed out.
28 * * * Request timed out.
29 * * * Request timed out.
30 * * * Request timed out.
Trace complete.

Tracert from server [MySiteIP] to client [ClientIP]
==============================
/root$ tracert "VisitorIP"
traceroute to "VisitorIP" ("VisitorIP"), 30 hops max, 40 byte packets
1 213.163.91.1 (213.163.91.1) 0.559 ms 0.833 ms 1.117 ms
2 10ge-3-1-0.br1.ams.we-dare.net (217.148.164.1) 1.353 ms 1.356 ms 1.507 ms
3 ge-0-3-0.br3.ams.we-dare.net (84.244.188.250) 1.749 ms 1.761 ms 1.840 ms
4 acr2-so-5-0-0.amsterdamamx.savvis.net (208.174.49.169) 1.744 ms 1.750 ms 1.827 ms
5 acr1-so-6-0-0.amsterdamamx.savvis.net (204.70.192.157) 1.732 ms 1.814 ms 1.938 ms
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