I have a car bay raspberry run ubuntu18.04+ros-melodic. i want to add a 4G module replace wifi that i can remote car in anywhere. but 4G module get not public IP ,so i cant connect this IP by direct. I find a port reverse proxy Intranet penetration，named FRP link text I make a TCP 22(SSH) and a TCP 11311,I connect raspberry by VM ubuntu18.04,it can see topic list, but when i run rviz to see image (from UVC camera),it is show NO received image. I run ROSWTF command,

Found 1 warning(s).
Warnings are things that may be just fine, but are sometimes at fault

WARNING The following node subscriptions are unconnected:
 * /rviz_1630379543635432692:
   * /tf
   * /tf_static
   * /map_updates
   * /scan
   * /map


Found 3 error(s).

ERROR Could not contact the following nodes:
 * /uvc_camera_node
 * /rosout
 * /compressed_image

ERROR The following nodes should be connected but aren't:
 * /compressed_image->/rosout (/rosout)
 * /rviz_1630379543635432692->/rosout (/rosout)
 * /uvc_camera_node->/rosout (/rosout)
 * /uvc_camera_node->/compressed_image (/camera/rgb/image_raw/compressed)

ERROR Errors connecting to the following services:
 * service [/compressed_image/get_loggers] appears to be malfunctioning: Unable to communicate with service [/compressed_image/get_loggers], address [rosrpc://clbrobot:36069]
 * service [/uvc_camera_node/get_loggers] appears to be malfunctioning: Unable to communicate with service 

[/uvc_camera_node/get_loggers], address [rosrpc://clbrobot:35253]
 * service [/camera/rgb/image_raw/compressed/set_parameters] appears to be malfunctioning: Unable to communicate with service [/camera/rgb/image_raw/compressed/set_parameters], address [rosrpc://clbrobot:35253]
 * service [/camera/rgb/image_raw/theora/set_parameters] appears to be malfunctioning: Unable to communicate with service [/camera/rgb/image_raw/theora/set_parameters], address [rosrpc://clbrobot:35253]
 * service [/uvc_camera_node/set_logger_level] appears to be malfunctioning: Unable to communicate with service [/uvc_camera_node/set_logger_level], address [rosrpc://clbrobot:35253]
 * service [/rosout/set_logger_level] appears to be malfunctioning: Unable to communicate with service [/rosout/set_logger_level], address [rosrpc://clbrobot:53271]
 * service [/set_camera_info] appears to be malfunctioning: Unable to communicate with service [/set_camera_info], address [rosrpc://clbrobot:35253]
 * service [/compressed_image/set_logger_level] appears to be malfunctioning: Unable to communicate with service [/compressed_image/set_logger_level], address [rosrpc://clbrobot:36069]
 * service [/camera/rgb/image_raw/compressedDepth/set_parameters] appears to be malfunctioning: Unable to communicate with service [/camera/rgb/image_raw/compressedDepth/set_parameters], address [rosrpc://clbrobot:35253]
 * service [/rosout/get_loggers] appears to be malfunctioning: Unable to communicate with service [/rosout/get_loggers], address [rosrpc://clbrobot:53271]

my raspberry ros is

export ROS_HOSTNAME=clbrobot
export ROS_IP=clbrobot
export ROS_MASTER_URI=http://clbrobot:11311

my PC VM ubuntu ROS is

export ROS_IP=192.168.31.31
export ROS_HOSTNAME=192.168.31.31

i run netstat -onlp,i fonud some port about uvc rosout tcp udp. I changed the ROSMASTERURI of the Raspberry Pi to the following

export ROS_HOSTNAME=clbrobot
export ROS_IP=10.2.48.200
export ROS_MASTER_URI=http://10.2.48.200:11311

I forwarded these ports, and then roswtf has no errors, only warnings, and the image of rvi still does not receive images

I think it should be a port problem. First of all, except for 11311, other ros-related ports seem to be changed, and they are different every time they are started. Even if it runs normally this time, I don't know how to do it every time in the future. I can't always check the port number and fill in the port forwarding every time I turn it on.

i need your help，Thanks