Why can't I read rtmp stream?

Question

Nginx

I did everything according to the guide from habr, I get an error ... I checked the rtsp stream on the VLC player, everything works fine. I substituted another rtsp stream (taken from the Internet), everything is fine again, but the target one does not want to work (
What could be the problem?

$ rtmpdump -r "rtmp://127.0.0.1:1935/cam1/stream" -v
RTMPDump v2.4
(c) 2010 Andrej Stepanchuk, Howard Chu, The Flvstreamer Team; license: GPL
WARNING: You haven't specified an output file (-o filename), using stdout
Connecting ...
INFO: Connected...
Starting Live Stream
ERROR: RTMP_ReadPacket, failed to read RTMP packet header
-0.001 kB / 0.00 sec
Download may be incomplete (downloaded about 0.00%), try resuming

Logs:

ffmpeg version N-80026-g936751b Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 4.8 (Ubuntu 4.8.4-2ubuntu1~14.04.3)
  configuration: --extra-libs=-ldl --prefix=/opt/ffmpeg --mandir=/usr/share/man --enable-avresample --disable-debug --enable-nonfree --enable-gpl --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-decoder=amrwb --enable-libpulse --enable-libfreetype --enable-gnutls --enable-libx264 --enable-libx265 --enable-libfdk-aac --enable-libvorbis --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libspeex --enable-libass --enable-avisynth --enable-libsoxr --enable-libxvid --enable-libvidstab
  libavutil      55. 24.100 / 55. 24.100
  libavcodec     57. 42.100 / 57. 42.100
  libavformat    57. 36.100 / 57. 36.100
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 45.100 /  6. 45.100
  libavresample   3.  0.  0 /  3.  0.  0
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
[rtsp @ 0x3cc1800] UDP timeout, retrying with TCP
[rtsp @ 0x3cc1800] method PAUSE failed: 455 Method Not Valid in This State
[rtsp @ 0x3cc1800] Could not find codec parameters for stream 0 (Video: h264, none): unspecified size
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, rtsp, from 'rtsp://login:[email protected]:port/cam/realmonitor?channel=2&subtype=0':
  Metadata:
    title           : RTSP Session/2.0
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: h264, none, 90k tbr, 90k tbn
Output #0, flv, to 'rtmp://localhost:1935/camera1/stream':
Output file #0 does not contain any stream