Plutonium

andresito_20 for the fps you just have to wait a little while like 5 mins before playing so it can load caches
and for the server connection thing try restarting the game by clicking the stop button on lutris and reopening it sometimes these things take a restart or two linux can be pretty iffy with network things i think youre just going to have to try everything like port forwarding allowing it through the firewall and changing compatibility settings in wine
for better fps try putting "com_maxfps <what you want your fps to be>" in the game console(~)

andresito_20 i have a few questions
1: do you have the 32 bit files for gamemode
2: which exact version of ubuntu do you have
3: which method did you use to install lutris
4: what are your pc specs
5: which drivers did you use
6: type "uname -r" into the console and paste what is said into a reply
7: send the full log

and here are some potential fixes
1: this one is potentially a bad idea though i dont know any other ways, uninstall your video drivers then reinstall them then do "sudo apt-mark hold <your driver name>" and make sure to install it thru the gui rather than terminal
2: delete any winetricks caches related to the game
3: clear "~/.local/share/lutris" "~/.config/lutris" "~/.cache/lutris"
4: completely reinstall lutris
5: try installing it on a seperate fresh install of ubuntu and then moving the files over and then click the plus for adding a game on lutris and select scan a folder for games
6: check hdd/ssd space
7: try installing plutonium through the plutonium .yaml file from "https://pastebin.com/raw/75BVbmR5" copy the text and go to where you want the .yaml file to be and type "touch plutonium.yaml" and open it with gedit and paste, then install it through lutris with the + button and then install from local install script
8: if none of this works for you try installing it manually using this guide "https://forum.plutonium.pw/topic/8261/guide-how-to-run-black-ops-2-zombies-on-linux"

also make sure to set its dxvk properly as sometimes games wont launch properly if its not the right version i use v1.7.1L