[CentOS] unreachable peer

Hey all,

I have a public peer system (yy.yy.yy.yy) that is reachable 
via my home uplink (xx.xx.xx.xxx).

15:59:30.244199 IP xx.xx.xx.xxx.42958 > yy.yy.yy.yy.https: tcp 0
15:59:30.281931 IP yy.yy.yy.yy.https > xx.xx.xx.xxx.42958: tcp 0
15:59:30.281945 IP xx.xx.xx.xxx.42958 > yy.yy.yy.yy.https: tcp 0
15:59:30.305020 IP xx.xx.xx.xxx.42958 > yy.yy.yy.yy.https: tcp 105
15:59:30.344004 IP yy.yy.yy.yy.https > xx.xx.xx.xxx.42958: tcp 1412
15:59:30.344013 IP xx.xx.xx.xxx.42958 > yy.yy.yy.yy.https: tcp 0
15:59:30.344016 IP yy.yy.yy.yy.https > xx.xx.xx.xxx.42958: tcp 23

 
At the office we have a EL5 based router that can not reach the 
mentioned system. It does not give any hint about the problem. 


15:57:51.751591 IP o.ff.i.ce.50902 > yy.yy.yy.yy.https: tcp 0
15:57:54.750834 IP o.ff.i.ce.50902 > yy.yy.yy.yy.https: tcp 0
15:58:00.749351 IP o.ff.i.ce.50902 > yy.yy.yy.yy.https: tcp 0
15:58:12.746408 IP o.ff.i.ce.50902 > yy.yy.yy.yy.https: tcp 0
15:58:36.740454 IP o.ff.i.ce.50902 > yy.yy.yy.yy.https: tcp 0
15:59:24.728605 IP o.ff.i.ce.50902 > yy.yy.yy.yy.https: tcp 0

I tried to connect with a removed ecn bit [1]

[1] https://en.wikipedia.org/wiki/Explicit_Congestion_Notification

but this was not the solution.

Any ideas? 

--
Thanks in advance!

LF