The portal server needs to be opened with the daily mission challenge.

yeah feel ya, the grind is real. I'm getting PTSD from World of Warcraft / black desert / rift etc, dang good I left those games . . . 

TLDR

Do challenges in casual breakthrough, it can be hard due to SUS / sweats but bots are there. 

I wish they allowed 2042 style solo coop (but with both sides) and portal pvp AI bots will full progression (but I think the XP gains was less than MP). . 

2042 had much faster progression, by lvl 50 I had over 10 guns with all accessories unlocked, multiple vehicles everything unlocked

BF 6 lvl 50 first four guns (I tend to go class specialties) and sidearm  are under lvl 20, 1/3 accessories, vehicles IFV lvl 10 and rest single digits / none. And this was using ALL my double XP hardware from opening day EA app fiasco. )

Detail

I just go in casual breakthrough, they got bots you can easily tag, plus they die a lot so you can just run around with paddles out and do the revive challenges. Though sometimes it's a headache cuz some ppl are sus (cheat) or they have a whole squad coordinating just to farm, or they have really good players looking to boost their K/D . But I got most of l my class challenges there (except the aircraft ones) and the breakthrough ones,. Now casual breakthrough has more maps so that's a plus. 

Yeah I wish they'd do like 2042 when I went in that game for the BF 6 battle pass. You could set up redacted rush 128 pvp AI bots. And bring back solo / coop with bots (and limit career XP but allow gun, hardware, vehicle XP and allow both sides (iirc 2042 solo / coop only let you go USA). 

Also the grind is **bleep** real. 2042 I was level 50, and I had all sniper and DMR accessories unlocked, even the 12X scopes that required 50+ headshots at 250 m  (but you could unlock 10X scope by just kills with that rife), both jets unlocked, both stealth and attack helos unlocked, MBT and IFV, and that doge ram, and pondhawk levelled up. I had my fav guns with most accessories. 

In BF 6 by level 50 (and this was burning all my hardware double XP tokens from the EA pro play opening day fiasco, BTW which after I found .out  . . only works at the end of the match when it's all calculated so pop them just before win / lose the match).  I only had starter guns, assault was 16, pistol 4, LMG 19 (main support), sniper 7, SMG 9, and less than half the accessories of the those start weapons, none other guns had unlocked accessories (beyond the starting ones it has to begin with). 

That said, I've found some strange bot lobbies, custom ones that give full XP like MP.  Like there was sobek 128 rush and one side was 16, two squads of players, rest bots. Other side was 112, two player squads and rest bots. I don't know how they figured it out because the Verified modes give less XP (if you hit a bot) AND only 16 bots max.

Another one was in the vehicle progression one, (it has all vehicles and 4 squads for players and reset bots), last weekend  my boyfriend was in, some guy spammed a portal code towards the end. It was the BR map, and it turned out to be a solo / coop style bot lobby that gave full MP XP and progression, it was nuts we were in there getting guns up, getting vehicle XP, and doing challenges. It was nerfed / removed by late Monday night PST.