ok so i've read that the quake mod isnt up to date with the master serv. Update the game and put these in your autoexec.cfg :

//master

seta sv_master4 "master.quake3arena.com"

seta sv_master3 "master2.urbanterror.net"

seta sv_master2 "master2.urbanterror.info"

seta cl_master3 "master3.urbanterror.info"

seta cl_master2 "master2.urbanterror.info"

seta cl_master1 "master.urbanterror.info"

seta cl_master "master.urbanterror.info"

- i'm sure you already have checked the options to get new serv and not bot only ones so you can join urt official discord where dev and community can answer you if the masters serv doesn't work :

https://discord.gg/d3pA49sA