How to get rid of `jitter buffer full` ffmpeg errors?

Question

fmpeg

How to get rid of `jitter buffer full` errors?
I am using ffmpeg from one of the last shots.

ffmpeg version N-90078-gf611fef Copyright (c) 2000-2018 the FFmpeg developers

The problem is that there is such a stream from the camera via rtsp:
ibb.co/fmckCc
From the camera side, this cannot be fixed, because!
I take it like this:

ffmpeg \
-strict experimental \
-fflags + genpts \
-fflags + latm \
-seek2any 1 \
-avoid_negative_ts + make_zero \
-max_delay 5000000 \
-rtsp_transport udp \
-i rtsp: // admin: @ 192.168.87.21: 554/0? .sdp \
-map 0 \
-r 15 \
-c: v copy \
-an \
-f mpegts udp: //239.0.0.1: 1234? ttl = 1? pkt_size = 1316

In the output I see the following errors:

[rtsp @ 0x154d180] jitter buffer full
[rtsp @ 0x154d180] RTP: missed 1 packets
[rtsp @ 0x154d180] jitter buffer full
[rtsp @ 0x154d180] RTP: missed 1 packets
[rtsp @ 0x154d180] jitter buffer full
[rtsp @ 0x154d180] RTP: missed 2 packets
[rtsp @ 0x154d180] jitter buffer full
[rtsp @ 0x154d180] RTP: missed 4 packets

because of this, the picture crumbles.
I increased the udp buffer in linux kernel settings:

net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.udp_mem = 8388608 12582912 16777216
net.ipv4.tcp_rmem = 4096 87380 8388608
net.ipv4.tcp_wmem = 4096 65536 8388608

But it didn't solve my problem.
How can you receive RTP correctly without loss?