I just moved to Ubuntu on my MacBook and I spent the whole day trying to open port 51413 for Transmission.
What I've already done:
I have ufw but I opened ports there and tried without it - probably not the problem:
51413/tcp ALLOW Anywhere 51413/tcp ALLOW Anywhere (v6) 21/tcp ALLOW OUT Anywhere 80 ALLOW OUT Anywhere 143 ALLOW OUT Anywhere 2049 ALLOW OUT Anywhere 110 ALLOW OUT Anywhere 135,139,445/tcp ALLOW OUT Anywhere 137,138/udp ALLOW OUT Anywhere 25/tcp ALLOW OUT Anywhere 631 ALLOW OUT Anywhere 443/tcp ALLOW OUT Anywhere 53/udp ALLOW OUT Anywhere 123/udp ALLOW OUT Anywhere 993/tcp ALLOW OUT Anywhere 465/tcp ALLOW OUT Anywhere 51413/tcp ALLOW OUT Anywhere
Router is Pirelli DRG A125G; tried disabling firewall, forwarding ports according to portforward.com but I have no experience with such thing so I don't know if I succeeded. On Transmission, it still shows the port is blocked and nothing is downloading.
CanYouSeeMe.org: Tried to use it to see if ports are open but it shows that port is blocked
Also tried qBittorrent, it also doesn't work.
51413
on udp too. More importantly what is your transmission configuration ?. You could try opening the wrong port. Also there is a port testing tool in transmission settings. No need to use an external one. If you allowed IGD/UPnP on your routeur, transmission should automatically take care of port fowarding, if you have enabled it. So again what is your transmission settings...