i could run squad battles using my custom settings too. however, in rush i would always disconnect after every foul or offside. now ive played several matches without the disconnect.
i did only two things -
one was going into the installation folder for FC 26 and going into the "_installer" folder and then i went into "EAAnticheat" folder. ran the anticheat which should open up a box and you then can select a bunch of games to uninstall/install/update or repair the anticheat for. i selected FC 26, uninstalled - reinstalled (maybe i did a repair too) and then updated it. i am sure i tried the game though and still disconnected...
i closed the game and looked for more solutions and read about the having all graphics set to "auto"...
this is the second thing i tried - i set them all to auto by using the "restore default" button, closed the game and then ran the game again and went to UT tried a rush match without disconnecting and its worked ever since... why its fixed for me i dont exactly know, but those are the only things i did haha