Thank you Dave and Khushboo for advises.
1) (re)moving 'pgadmin4.db' - did not help.
2) I have disabled teredo - did not help.
3) localhost is resolved to IPv6 address:
$ ping localhost
Pinging ogrodowa [::1] with 32 bytes of data:
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
4) I DO use IPv4 as well.
5) No entries for localhost in hosts file.
6) On which address/port the server should be listening?
$ netstat -a | grep LISTEN | grep "127.0.0.1"
7) ping to 127.0.0.1 works well:
$ ping 127.0.0.1
Pinging 127.0.0.1 with 32 bytes of data:
Reply from
127.0.0.1: bytes=32 time<1ms TTL=128
Reply from
127.0.0.1: bytes=32 time<1ms TTL=128
Reply from
127.0.0.1: bytes=32 time<1ms TTL=128
Reply from
127.0.0.1: bytes=32 time<1ms TTL=128
Not sure what else I need to check...
Thank you and kind regards
Pawel