The huge (over 3 GB in size) big update for Verdun which has been released today, makes it possible to switch seamless to the front of Tannenberg (if installed).

Also it changes a lot "under the hood":

Changelog - DEFAULT V270.8489 18-01-2018
Reverted the strafing bugfix
Removed audio from stance switching(crouching sound)
Fixed scoreboard (had narrow rows and gaps between squads)
When not spawning on a player, you will now look in the correct direction on spawn
Switching fronts will no longer show a buy message when you've already bought the front, but don't have it installed (correctly)
Fixed incorrect banning on OSX

Changelog - DEFAULT V270.8475 18-01-2018
Updated Graphics
New Image Effects
Deepsky Fog system
Reflection Probes
Screenspace shadows
Added ingame front switching between Verdun and Tannenberg.
Added Bullet penetration to Verdun
Added 1p gas choking animation
Adjusted default controls:
Prone F -> Left Ctrl
Melee V -> F
Use B -> E
Voice Chat E -> Left Alt
Added match end game camera animations
Always full accuracy through ironsights. With some weapons, especially pistols, accuracy wasn't always 100% when sighting. On longer distances this resulted in quite some deviation.
Better out of the box controller support
Adjusted weapon values according to https://docs.google.com/spreadsheets/d/194f3UsP6uosJqZQKTJpAUotL9Qb1e2xI...
Bots adjustments
Changed the shooting behavior of bots so they will no longer leave ADS after every shot
Bots can now perform melee attacks
Bots can now throw grenades
Bots will now run away from enemy grenades
Bots no longer walk while shooting
Suppression nerf:
Both melee and ranged: Lower strength, Quicker centertime
Ranged: You can now only get so much flinches in a certain timeframe
Melee suppression: Bayonets and flamethrower cause less flinch
Added recoil kick to LMGs
Highered default terrain detail on Low Terrain quality so it is more accurate(Fixes people hiding in terrain or people actually being behind terrain althogh you don't see a terrain)
Your gun will now always move a bit when holding breath while walking(was bugged before and exploitable)
Performance improvements for generating the after action report when the match has ended
Detect windows 7 issue that required admin privs and warn the user about that
You can now create a private match without a password (admin password is still required)
Fixed matchmaking bug: Lobby squads from 'Create squad' will now always try to join the room with most players
Slightly longer grenade throw time so animation doesn't look that frantic
Added Resolution Scale: Renders the game at a fixed resolution relative to the screen resolution. Higher than 100% means more detail, less aliasing. Lower than 100% is could give performance gain on some machines at the cost of resolution.
Graphics options: windowed mode, resolution and refresh rate now always matches the actual used values. Refresh rate is also no longer visible in windowed mode, because it's only used in full screen
Bots will no longer shake when not aiming at someone
When you miss the spawn wave because you were in the death camera animation, you'll now instantly spawn afterwards
You can now toggle all text and voice chat with the chat commands "/textchat [on/off]" and "/voicechat [on/off]"
Some network performance improvements: Reduced network messages
Optimized player data over network
New medal for Verdun: "Most binoc kills"
Cache account stats in memory to prevent lagspikes during gameplay (Arty kill and a few other instances)
Updated multiplayer library. Thisupdate has a few minor performance improvements. Also fixes a rare disconnect issue.
Fixed a die RPC sometimes being dropped, could fix a rare case where shots did not register
Increase level load speed a tiny bit and reduce memory usage
Improved tree rendering performance
Fixed ground detection
You can no longer close the loadout menu in Attrition and RDM before your first spawn
Less death screams/gurgles
Greatly reduce time between allowing matchmaking to place squads in 1 certain match(30 -> 15): Will reduce the amount of smaller side matches being created. Also increase time required before starting a new match (10 -> 30), also to prevent creating several smaller matches.
When "Always show tactical view" is disabled, pressing the tactical view button will no longer open the view while chatting or changing squad name
3p reload animation matches 1p animation more closely
For all network room operations: ensure the list gives fullest rooms first so that we always try to join fullest rooms first.
Fixed specific gore issue logs ('hoe vaak komt deze rare corpse use case voor', 'we destroy a corpse but..', 'at least make sure this doesn't hang death state')
Fixed non-responding input when closing the loadout menu in RDM and Attrition
Fixed animation glitch when starting sprint during weapon unsight
Update Douaumont: fixed access to fort stairs, fixed roof toehold, fixed hole in fort/terrain, fixed access to rooms/holes, fixed route up bunker.
Removed unnecesary collion from very thin pigtails which might cause clunkiness and shots not registering
Changing the room size in a private match will now update the maximum number of players on the scoreboard
Headbob causes less cam hiccups when moving/stopping
You'll no longer receiving points for ending a killstreak when you commit suicide or kill a friendly
You can no longer get pushed by other players
Interrupting reload also stops reload sounds
Fixed health regen delay being 0 during first player life
Now terminate the game with an error if we detect that steam didn't update properly, wil automatically verify files.
Fix "||" in username breaking online auth
Repeating weapon types will no longer spawn another case when the reloading/recharging has been interrupted and a case has already been ejected
GRENADE_TRAINING_3 now correctly gives extra score
Loading screen will now show the correct weather when loading a new map
Fixed bug where squad defence wins would count toward 'highest multi kill' stat instead of win streak
When Squad Missing does happen, matchmaking will now ignore that game, unless you manually join it
Chat table won't grow out of screen anymore when filled with multiline labels
Removed Fernglas inscriptions to make the binoculars generic for both sides.
You can no longer deploy while jumping
Made it harder to stand on heads
'bolt wrong' icon indicator
Fix against displaying negative ammo in HUD
Added Discord Rich Presence support (Windows only). If you use Discords overlay, will show you what map & mode you are playing.
Fixed syncing of inventory sometimes getting messed up when joining a game while someone is changing weapons
Texture quality less heavy on performance
Game will try to use your Steam name instead of nagging for a new name input
When joining a game, reduce incoming network messages by over 50%
You can now abort reloading by clicking
Made it less easy to spam the chat with walls of text
Your previous role icon doesn't stay yellow anymore in score board after switching squad
Melee shock should only be caused by running people with melee weapons also it shouldn't trigger unless enemy and victim are facing each other
Other players will now always spawn directly in their correct stance
Sharpening is now a graphics setting
Added squad chat (default key: I)
Tooltips stay longer
Removed deprecated screenshot function on F11 key which only messed with your screen.
Voicechat is louder
Resolution setting now includes Refresh Rate setting
BlackMill Splashscreen
Ammo Crate re-fill is now on 'Use' button instead of 'Reload'
The camera was sometimes rotated after spawning
Fixed melee ranges not always applying to melee weapons properly

Source: http://steamcommunity.com/app/242860/discussions/0/365163686050549961/