Custom Campaigns borderline impossible solo?

Just give yourself some advantage with mods and they are playable

No, no, they were made to be hard/unfair, so don't feel bad.

Best advice I can give you is to (ab)use the pause since you are playing solo.

@inspexor All the missions are possible solo and were completed.
I've uploaded some the most difficult ones such as Blockade on my YT. So feel free to check them out how I play the start and adapt the core thoughts to your own gameplay.
https://www.youtube.com/@sladow5975/videos
If you have recommendations about other missions, feel free to let me know. I'll have quite some time after the next couple of days so I can upload it. Feel free to DM me via Discord as well if you need specific advice.

Inactive.

@sladow-noob I can only find a video about "Blockade" where you show the opening. I've roughly copied what you did and i could (barely) fend off the first waves of attacks but i got absolutely wrecked as soon as the map expanded for the second time.
There are so many units thrown at you at once that my game started lagging.
Whoever made this map is either a top 1% player or didn't test it properly is my guess.

My understanding is the Seraphim custom campaign is intended to be played by multiple people (not solo) [Edit: was wrong on this point - its only some of the custom missions that are intended for multiple players], so you could try playing co-op online or with an AI buddy (M28 and possibly RNG although I've not tested it can work as teammates in campaign missions). In the case of M28 if it's too weak you could make it an AiX teammate and set the AiX modifiers to a level that works for you.

Since you mention medium difficulty I'm also assuming you've lowered the difficulty setting (as it defaults to hard).

You could also provide feedback in the campaign discord:
https://discord.gg/9ddQ4kRgBY

@inspexor I did two of the standard FA missions and "Crystals", the latter being private though cuz I'm not a huge fan of my opening there.

Custom FAF missions (e.g. Blockade, Crystals etc) are meant for better players as they're harder and for multiple ones, because they do not scale with player amount.
Sera missions are also not the easiest ones yet they're meant for solo.

I linked you my account not because I wanted to say "do exactly this and it'll be easy" but as a "every mission is in theory possible solo and people have done this". Personally I've tested the harder missions myself and provided feedback on the Discord.
As Maudlin mentioned, you can also add a decent AI to your team. Besides that the missions vary in difficulty as they're not only meant for the lower ranked players and will probably require either adjusting the difficulty itself or to activate some mods to help you (note that ressource mods also affect the scripted AIs).

Inactive.

Also if you struggle with a different mission I've not made a video about, please feel free to tell me and I can create one within a couple of days.

Inactive.

As an addition to what I've said:
Feel free to post feedback either directly on the FAF coop discord or here

For the missions Greenkiller added both the authors and whether the missions are already on the coop tab or if you have to download them manually from the Discord in order to play them ("Unreleased"). For providing feedback feel free to reach out to the author.

Reworks and Modifications
Vanilla UEF
M06 (Grandpa Sawyer)

Vanilla Aeon
M02-M06 (Speed2)

Vanilla Cybran
M04 (Speed2)
M05 (Grandpa Sawyer)

Seraphim Campaign (solo):
Created by Shadowlorda1
M1: Yath-Aez
M2: Tha-Atha-Aez
M3: Uhthe-Thumm-QAI
M4: Ioz-Shavoh-Kael
M5: Overlord-Surth-Velsok
M6: Operation-Thisl-Eniz
Custom:
Operation Zyne Aez

Coalition Campaign (Coop):
Created by Shadowlorda1
M1: Blockade
M2: Holy Raid
M3: Golden Crystals
M4: Rebel's Rest
M5: Red Revenage
M6: End Game (Unreleased)
Custom:
Titanfall (Unreleased)

Custom Missions:
Novax Station Assault (Speed2)
Operation Tight Spot (Speed2)
Global Warning (4z0t)
Operation Trident

Inactive.

Thanks for the list Sladow Noob
Checking it I see some maps which I'm unable to find on the discord Channel (Operation Zyne Aez, M6: End Game, Titanfall )
I usualy look on the public upload section. Can they be found elsewhere ?

Thanks to advise

@flankker Those 3 that you mentioned are WIP & are Unreleased.

@greenkiller56 was kind enough to edit the list in the #getting-started channel to include the download links to the latest versions of each map that is currently released.