Thanks guys for the responses. They set me on the way toward a possible resolution, which I haven’t yet achieved.

SOME CLARIFICATIONS:

1.?????? The Putty error message is - Network Error: Software caused connection to abort.

2.?????? Several different Putty “keep alive” time setting failed to prevent the problem.

3.?????? The problem is not router based. At the abort Putty stays connected to the RPi, only the login to RPi is broken. Also the router log shows no activity at the time of the problem.

4.?????? If the RPi WSPR TX is run directly on the RPi (no SSH), the login does not break even after hours of activity and also does not break at 01:30 to 02:30 UTC as it does when run via SSH.

I believe these indicate that the problem must be with the RPi’s SSHD implementation.

ACTIONS TAKEN:

1.?????? root/usr/share/openssh/sshd_config was edited to enable ClientAliveInterval and set its value to 14400 (4 hours) and to enable ClientAliveCountMax and set its value to 3. This provides 12 hours of daylight operation, but does not stop the abort at 01:30 UTC. There are probably about 30 possible settings in my sshd_config, but only 3 (5 with my changes) are enabled. I guess the defaults are generally OK, or should others be enabled?

2.?????? As suggested, I have viewed dmesg. but all I see there seems to relate to boot up, not loss of login. Most of the other Internet advice about sshd logs is generic Linux and references files that I don’t find on my RPi.

3.?????? I have looked at the log files in root/var/log. The applicable files all carry a time stamp consistent with my logging back into Pi again after the abort. The only one that I can read is debug and there is nothing in it with a time stamp consistent with the abort – all times are for my re-logging into Pi.

?? So the problem remains, and any further suggestions would be appreciate.

Thanks,

Tom???? K4ZAD