so ive been messing with Winlink Express for about three weeks now and i think im close but not quite there. running a Kenwood TS-590SG into a SignaLink USB, got Vara HF licensed and everything seemed fine during the initial handshake tests. the problem is when i actually try to send a message through an RMS gateway it connects, does the banner exchange, starts the session, and then just drops somewhere in the middle of the transfer. doesnt matter which gateway i pick, tried a few different ones within reasonable distance, same deal every time.

at first i thought it was my audio levels so i spent like two days tweaking the SignaLink trim pots and watching the waterfall in WSJT-X to make sure i wasnt overdriving anything. levels look reasonable, maybe a little hot but nothing crazy. then i thought maybe it was a timing issue with the PTT so i added some extra tail delay in Vara but that didnt seem to help either.

the Winlink session log just says something like "connection reset" or "peer disconnected" which isnt exactly descriptive. has anyone seen this specific behavior where the handshake works fine but the actual message transfer falls apart? im starting to wonder if its something on the gateway end or if my setup is just wrong somewhere. would really appreciate any ideas before i completely tear everything down and start over.

yeah that sounds like it could be an ALC issue biting you. the handshake tones in VARA are pretty forgiving but once it starts pushing actual data the duty cycle goes way up and if your ALC is kicking in mid-transmission you'll get corrupted packets and the gateway drops you. check if your ALC meter is moving at all during the send — it should basically be sitting still. if it's bouncing around your power is way too high for that setup.

also worth checking is whether your rig's built-in voice processor or any compression is enabled. that stuff will murder a data signal. on the 590 make sure the speech processor is off and also check the DATA mode settings in the menu — there's a separate audio input level for the ACC2 jack versus the front mic input and sometimes people have those mixed up. the SignaLink should be going into the rear data port not the mic jack if you want the cleanest path.

one more thing — what baud rate are you running VARA at? if you're on a noisy band and trying to push 2750 or whatever the high setting is, try dropping it down and see if your sessions complete. sometimes a slower more reliable connection is better than a fast one that keeps falling over.

had almost this exact same problem last year, turned out my firewall was blocking something in Winlink Express and the session would partially complete then just die. i know that sounds weird for a radio thing but the software does phone home during sessions and if that call fails it can behave strangely. probably not your issue but worth checking the Winlink event log in the program itself, not just the session log — theres more detail in there about whats actually happening on the software side.