I'm in the same boat here with my Titan. It's kind of crazy tbh, because all of my characters are legacy characters, I only played during the Vanilla Destiny 2 and Osiris Xpacs. My warlock I have been maining for 2-3ish weeks and now that I'm 1807 I decided to do the old school "boost your light level" by transferring guns over to your lowers. I threw them on my hunter, got it up to 1777, then I realized you could cash engrams out that you earned on other characters and so I logged on my titan and immediately "boosted" him to 1800. Dropped a 100k Glimmer on aspects and fragments and stuff, found some decent statted gear, used my upgrade modules, and then some time last night a few missions AFTER boosting him, and playing around with him, I got Dc'd halfway through a mission with Error Code Monkey. I tried Relogging, restarting PC, restarted the router. I use google DNS already, flushed my network cache, I don't use a VPN, and I have very reliable 800 down 35 up speeds. I work in I.T. not that it's prevalent, but I assure you after going through every piece of hardware/software between me and that Destiny 2 server I control, it's not hardware/network related on my side. It ONLY happens on my Titan, I made sure to bounce to my Warlock and Hunter, and I can play them just fine. Doesn't matter where I am, where I go, the moment I kill anything, I'm kicked back to orbit with Error Code: Monkey. I have No sunset gear, no old exotics, I have all my fragments and aspects equipped, I even went so far as to delete any sunset gear in my inventory. This is clearly an actual issue, on Bungie's end, and I'm not upset that there's an issue, I'm upset that the ONLY answer I can find, here or reddit or google (and I HOPE TO GOD, that NO ONE in bungie said this, not saying you guys did) is to make a new character. That is not acceptable, so I mean if you want to clone my items and -blam!-, and then put them on a "new" character that's fine, but I'm gonna need my progress, my subclasses, the gear I'm wearing ALL that -blam!-! Please and Thank you!

it's a bug with OLD characters, if you create a new one, that one will work fine... I have the same problem and did that , so i'm playing with a new character with everything locked ... :(