Make sure you are fully connectable (port forwarded). To check this you will want to test your torrent client’s incoming connection port with a 3rd party port test website e.g. www.canyouseeme.org, www.yougetsignal.com/tools/open-ports/, portchecker.co, etc. Those websites should be able to successfully connect to your torrent client’s incoming connections port. If the test fails then you need to look at adding an incoming port forward in your network router’s configuration.
Also make sure DHT/PEX is enabled in your torrent client (those are enabled by default).
PS - The above is if you’re not using a VPN/Proxy (you didn’t mention using one)… definitely don’t re-configure your router configuration if you intend to use a VPN/Proxy, all port forwarding needs to happen on the VPN/Proxy server in those cases.