Good Morning

Now I have tried some experiments with the SSH tunnels already.
Interestingly, I can't reach certain web servers through the tunnel, e.g. those of the local routers (ISP cable modem).
The Apache2 server on the Linux machines I can reach without any problems.
It must probably still be a setting in the ssh_config?

Here the output after the following command: SSH -R 8888:"router-ip":80 -p "port number on remote machine" "IP address remote machine"

ring@mac1-ring:~$ debug3: receive packet: type 90
debug1: client_input_channel_open: ctype forwarded-tcpip rchan 3 win 2097152 max 32768
debug1: client_request_forwarded_tcpip: listen localhost port 8888, originator 192.168.1.148 port 50993
debug2: fd 7 setting O_NONBLOCK
debug2: fd 7 setting TCP_NODELAY
debug1: connect_next: host 192.168.1.1 ([192.168.1.1]:80) in progress, fd=7
debug3: fd 7 is O_NONBLOCK
debug3: fd 7 is O_NONBLOCK
debug1: channel 1: new [192.168.1.148]
debug1: confirm forwarded-tcpip
debug3: channel 1: waiting for connection
debug1: channel 1: connected to 192.168.1.1 port 80
debug3: send packet: type 91
debug3: receive packet: type 90
debug1: client_input_channel_open: ctype forwarded-tcpip rchan 4 win 2097152 max 32768
debug1: client_request_forwarded_tcpip: listen localhost port 8888, originator 192.168.1.148 port 50992
debug2: fd 8 setting O_NONBLOCK
debug2: fd 8 setting TCP_NODELAY
debug1: connect_next: host 192.168.1.1 ([192.168.1.1]:80) in progress, fd=8
debug3: fd 8 is O_NONBLOCK
debug3: fd 8 is O_NONBLOCK
debug1: channel 2: new [192.168.1.148]
debug1: confirm forwarded-tcpip
debug3: channel 2: waiting for connection
debug1: channel 2: connected to 192.168.1.1 port 80
debug3: send packet: type 91
debug2: channel 1: read<=0 rfd 7 len 0
debug2: channel 1: read failed
debug2: channel 1: chan_shutdown_read (i0 o0 sock 7 wfd 7 efd -1 [closed])
debug2: channel 1: input open -> drain
debug2: channel 1: ibuf empty
debug2: channel 1: send eof
debug3: send packet: type 96
debug2: channel 1: input drain -> closed
debug3: receive packet: type 96
debug2: channel 1: rcvd eof
debug2: channel 1: output open -> drain
debug2: channel 1: obuf empty
debug2: channel 1: chan_shutdown_write (i3 o1 sock 7 wfd 7 efd -1 [closed])
debug2: channel 1: output drain -> closed
debug3: receive packet: type 97
debug2: channel 1: rcvd close
debug3: channel 1: will not send data after close
debug2: channel 1: send close
debug3: send packet: type 97
debug2: channel 1: is dead
debug2: channel 1: garbage collecting
debug1: channel 1: free: 192.168.1.148, nchannels 3
debug3: channel 1: status: The following connections are open:
#0 client-session (t4 r2 i0/0 o0/0 e[write]/0 fd 4/5/6 sock -1 cc -1)
#1 192.168.1.148 (t4 r3 i3/0 o3/0 e[closed]/0 fd 7/7/-1 sock 7 cc -1)
#2 192.168.1.148 (t4 r4 i0/0 o0/473 e[closed]/0 fd 8/8/-1 sock 8 cc -1)

What command are you using on the client machine, and what output do you get?

I still reckon you'd be best off using a VPN for this... you get more flexibility, it is more robust and even a little more secure.

With an ssh tunnel, if you reboot the client machine the process will die on the server.