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