I can see it and pinging works from Poland:


$ ping b.tile.openstreetmap.org
PING germany-01.tile.openstreetmap.org (144.76.70.77) 56(84) bytes of data.
64 bytes from katie.openstreetmap.org (144.76.70.77): icmp_seq=1 ttl=54 time=49.6 ms
64 bytes from katie.openstreetmap.org (144.76.70.77): icmp_seq=2 ttl=54 time=53.7 ms
64 bytes from katie.openstreetmap.org (144.76.70.77): icmp_seq=3 ttl=54 time=50.6 ms

If you have some problems with tiles, try contacting OWG:

https://github.com/openstreetmap/operations