Nope. I'm very new to the Switch scene. Literally got my switch a week and a half ago, and I was on vacation last week so I didn't do much tinkering with it at all yet. Acquired some backups of some games, tried them. They worked. Tried them online, got a 2124-4025 error on all. And did a little more research here in this very thread to figure things out. Multiple suggestions were to use large, offline game certs.. one for type 1 and one for type 2 carts. Okay... Tried that. Extracted certs from BotW and LEGO Incredibles and applied the appropriate type certs to all of my backups. They all worked great online! I was both surprised and happy! And then I woke up the next morning to find all had the 2124-4025 again. Based on the fact that I can still get to the eShop and play Fortnite, that my unit hasn't been banned... just the certs. I may be mistaken. Until somebody tells me otherwise, I've removed all WiFi data from the unit so it can't go online at all. For the record, I'm in the USA.
Based on the speed this community is addressing things, I'm betting a solution is just around the corner. (Cert algorithm generator? :-) )