KTorrent cannot find peers and download files, whereas Transmission can (cellular 4G)

English Network/Internet
1

KTorrent works OK with 1st ISP connected by Ethernet cable, cannot download files with using cellular 4G (2nd ISP). Sometimes KTorrent downloads files with cellular 4G.
Transmission works OK in every case.

I turned on uTP protocol and DHT in KTorrent, also peer exchange, webseeds, etc. After turning on uTP protocol and DHT and some other settings KTorrent starts to work, but stops after stop - start of KTorrent.

Packages info:

:~> LANG=C zypper se -si ktorrent transmission
Loading repository data...
Reading installed packages...

S  | Name                  | Type    | Version           | Arch   | Repository
---+-----------------------+---------+-------------------+--------+----------------
i+ | ktorrent              | package | 23.08.5-bp156.1.2 | x86_64 | Main Repository
i+ | ktorrent-lang         | package | 23.08.5-bp156.1.2 | noarch | Main Repository
i+ | libktorrent-lang      | package | 23.08.5-bp156.1.1 | noarch | Main Repository
i+ | transmission          | package | 4.0.5-bp156.1.2   | x86_64 | Main Repository
i  | transmission-common   | package | 4.0.5-bp156.1.2   | noarch | Main Repository
i  | transmission-gtk      | package | 4.0.5-bp156.1.2   | x86_64 | Main Repository
i  | transmission-gtk-lang | package | 4.0.5-bp156.1.2   | noarch | Main Repository
i+ | transmission-qt       | package | 4.0.5-bp156.1.2   | x86_64 | Main Repository
i  | transmission-qt-lang  | package | 4.0.5-bp156.1.2   | noarch | Main Repository
2

KTorrent cannot connect to tracker?

3

KTorrent works via http proxy. Not fast, but it works.

4

KTorrent works OK after disabling IPv6 via NetworkManager “Method=Disabled”, setting “Method=Ignored” doesn’t help.
Also some sites don’t work with enabled IPv6.

When using 1st ISP connected by Ethernet cable - IPv6 was disabled.

5

Errors in realization of IPv6 at cellular ISP network?

6

There are some glitches with cellular ISP, disabling IPv6 via NetworkManager “Method=Disabled” helped only partially.

Sometimes KTorrent can connect to tracker, sometimes - not.
Sometimes KTorrent can download files without tracker, sometimes - not.

Transmission works more reliably.
Torrent clients need the newest torrent file to work properly.