Which ISP is at fault here?

[Holodene]

See the 140ms spike. Reckon it's Cogent congestion? It has been this way for several weeks.

Code Select Expand

Tracing route to XXXX.cm-x-x.dynamic.ziggo.nl [XXXX]
over a maximum of 30 hops:

  1    <1 ms    <1 ms    <1 ms  192.168.1.254
  2    30 ms    31 ms    29 ms  telehouse-gw2-lo1.idnet.net [212.69.63.51]
  3    30 ms    30 ms    31 ms  telehouse-gw5-e4-400.idnet.net [212.69.63.245]
  4    50 ms    31 ms    29 ms  gi8-27.mpd01.lon02.atlas.cogentco.com [149.6.148.205]
  5    31 ms    30 ms    30 ms  te1-2.ccr02.lon02.atlas.cogentco.com [130.117.50.117]
  6    38 ms    41 ms    43 ms  te0-2-0-0.ccr22.ams03.atlas.cogentco.com [130.117.1.169]
  7    37 ms    39 ms    39 ms  te7-2.mpd01.ams04.atlas.cogentco.com [154.54.36.130]
  8   127 ms   128 ms   132 ms  149.6.128.254
  9   130 ms   129 ms   129 ms  gn-rc0002-cr102-ae0-0.core.as9143.net [213.51.158.17]
10   133 ms   133 ms     *     csw2-ge1-1.hnglo1.ov.home.nl [213.51.158.111]
11   138 ms   134 ms   137 ms  csw2-pc105.deven1.ov.home.nl [213.51.133.59]
12   139 ms   132 ms   123 ms  ubr12-ge0-2-202.deven1.ov.home.nl [213.51.133.190]
<snip>
25     *        *      140 ms  XXXXX.cm-x-x.dynamic.ziggo.nl [XXXX]

[pctech]

Very definitely looks to be within Cogent's network.

Maybe support can give their NOC a nudge but it'll be up to them whether they do anything.