Okay, I finally got through to Marius's BBS. Don't know what the holdup was before.
Anyway, using my Atari STacy and the UDS10, I got through and had no problems
whatsoever. No funny characters at all and everything worked as expected.
I got another answer back from the tech at Lantronix as well. I had described to
him some of the things we had tried and were seeing. Here is his latest response:
(this response was given before I was able to logon successfully to Marius's BBS, btw)
Have you looked at the configuration of the UDS1100 that called in and did not have issues?
Another thing we may want to try would be to back up to the basics. Factory flush the serial settings and do a simple socket connection by changing one of the units to connect mode C5 and configure a remote IP address and port of the other unit. Then use hyperterminal sessions to pass data back and forth.
It looks like the J and M are printed representations of ctrl-j and ctrl-m of line feed and carriage return, respectively.
Note that a tunnel between UDS's should generally be RAW TCP. We changed the setting to this, but that means that when a telnet client connects (like HyperTerminal) it becomes a telnet to RAW connection. This causes issues in the way ctrl-j and ctrl-m are handled. PuTTY supports RAW connections. You may want to try a PuTTY RAW connection to the UDS1100.
Ultimately, if there is some quirky modem mode compatibility issue between the older UDS-10 and the UDS1100, it may be that both sides need to be UDS1100's. Based on the information, it looks like the issue might be on the UDS-10 side.
As soon as I get some more info/time, I'll update him and see what he says then. The guy is working really hard to try and help, I'm a bit impressed.