How do I continuously stream multiple .mp4 files with ffmpeg to an rtmp server?

Question

I am an Software Engineering trainee and I need to make a video stream that continuously streams several videos on repeat.

I have made an rtmp server using nginx and their rtmp module and as streaming software I am trying to use ffmpeg

Thus far I am able to screen capture the whole screen of the server and I can stream 1 single video.

I need to stream several videos, probably with several lengths on repeat 24/7. I found some tips on the internet and it bought me to this command:

sudo ffmpeg -re -f concat -safe 0 -stream_loop -1 -i ./root.txt -an -c:v libx264 -preset veryfast -maxrate 6000k -bufsize 100000k -pix_fmt yuv420p -g 50 -fflags +genpts -f flv rtmp://ip-adress/application/key

the root.txt file contains the lines:
file 'nested.txt'
file 'nested.txt'

the file nested.txt contains:
ffconcat version 1.0
file 'earth.mp4'
file 'rabbit.mp4'

The problem I have is that when ffmpeg tries to stream the second video(rabbit.mp4) then it gets stuck and just streams the same frame. Also the client(VLC) just stops.

frame= 875 fps= 26 q=29.0 size= 2363kB time=00:00:28.70 bitrate= 674.5kbits/
frame= 888 fps= 26 q=29.0 size= 2388kB time=00:00:29.13 bitrate= 671.5kbits/ [mov,mp4,m4a,3gp,3g2,mj2 @ 0x5634606e1cc0] Auto-inserting h264_mp4toannexb bitstream filter

frame= 900 fps= 26 q=29.0 size= 2413kB time=00:00:29.53 bitrate= 669.3kbits/

frame= 900 fps= 26 q=29.0 size= 2413kB time=00:00:29.53 bitrate= 669.3kbits/

frame= 900 fps= 25 q=29.0 size= 2413kB time=00:00:29.53 bitrate= 669.3kbits/

How can I fix this problem that the stream gets stuck when he switches between videos?

My internet searches have not found a solution.

edit: the output of ffmpeg -i earth.mp4 -i rabbit.mp4

 ffmpeg version 4.2-0york0~18.04 Copyright (c) 2000-2019 the FFmpeg developers  
  built with gcc 7 (Ubuntu 7.4.0-1ubuntu1~18.04.1)  
  configuration: --prefix=/usr --extra-version='0york0~18.04' -- 
 toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl   --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-nonfree --enable-libfdk-aac --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 31.100 / 56. 31.100  
  libavcodec     58. 54.100 / 58. 54.100  
  libavformat    58. 29.100 / 58. 29.100  
  libavdevice    58.  8.100 / 58.  8.100  
  libavfilter     7. 57.100 /  7. 57.100  
  libavresample   4.  0.  0 /  4.  0.  0  
  libswscale      5.  5.100 /  5.  5.100  
  libswresample   3.  5.100 /  3.  5.100  
  libpostproc    55.  5.100 / 55.  5.100  
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'earth.mp4':  
  Metadata:  
    major_brand     : mp42  
    minor_version   : 0  
    compatible_brands: mp42mp41isomavc1  
    creation_time   : 2015-08-07T09:13:36.000000Z  
  Duration: 00:00:30.53, start: 0.000000, bitrate: 4675 kb/s  
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv,   bt709), 1920x1080 [SAR 1:1 DAR 16:9], 4486 kb/s, 30 fps, 30 tbr, 30 tbn, 60 tbc   (default)  
    Metadata:  
      creation_time   : 2015-08-07T09:13:36.000000Z  
      handler_name    : L-SMASH Video Handler  
      encoder         : AVC Coding  
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo,   fltp, 256 kb/s (default)  
    Metadata:  
      creation_time   : 2015-08-07T09:13:36.000000Z  
      handler_name    : L-SMASH Audio Handler  
Input #1, mov,mp4,m4a,3gp,3g2,mj2, from 'rabbit.mp4':  
  Metadata:  
    major_brand     : isom  
    minor_version   : 512  
    compatible_brands: isomiso2avc1mp41  
    creation_time   : 1970-01-01T00:00:00.000000Z  
    encoder         : Lavf53.24.2  
  Duration: 00:02:50.86, start: 0.000000, bitrate: 1474 kb/s  
    Stream #1:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720   [SAR 1:1 DAR 16:9], 1086 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)  
    Metadata:  
      creation_time   : 1970-01-01T00:00:00.000000Z  
      handler_name    : VideoHandler  
    Stream #1:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp,   383 kb/s (default)  
    Metadata:  
      creation_time   : 1970-01-01T00:00:00.000000Z  
      handler_name    : SoundHandler

edit nr 2: Thanks to Gyan i figured it out.

my two files had indeed not the same codecs.

so I just encoded the files again with

ffmpeg -i file.mp4 -c:v libx264 outputFile.mp4

And now the stream works. i can even change the playlist and as long as the files have the same codec, the files will be streamed.

Thnak you again !