Found this thread whilst looking for ideas with a similar problem. No changes in environment at all but suddenly signal was going up and down and dropping after 2 years of trouble free use. Tried the usual solutions - new batteries (3 sets!), checked controller id (0), factory reset (deleted 40 locos!) and dropped an email to Bachmann (waiting for response). I also have a Belkin router so thought "what the heck, I'll try it" and lo! Dynamis works again. BUT! Turning the router back on, doesn't bring back the same problem which makes me wonder if there's something else causing interference.
However, all is working again (for now) but I'll be saving my pennies for a new system I think. (Need to find another job first tho!)
Only thing is .. I LIKE my dynamis. It does everything I want - runs 4 locos simultaneously, 40 loco database not limited to a 2 loco stack, trigger/latch functions for sound locos and it's not a console. It has a large, clear display free of hieroglyphics and it didn't cost the earth. Decisions! Dec isions!
at least I can play trains again