I'm trying to start using Ubuntu. I already had Windows 10 in my hdd, I made a new partition for Ubuntu 18.04 and then installed it. Both OS are in the same hdd but in different partitions, but when I boot it shows the grub and it won't show Windows 10 option, it shows Windows Boot Manager (and if I pick this it will let me boot in Windows but it's slow). I already tried os-prober (from this question: GRUB does not detect Windows) and this is what it shows
/dev/sda2@/EFI/Microsoft/Boot/bootmgfw.efi:Windows Boot Manager:Windows:efi
when I use fdisk -l this is what it shows (in Spanish, I'm sorry)
Disco /dev/sda: 931.5 GiB, 1000204886016 bytes, 1953525168 sectores
Unidades: sectores de 1 * 512 = 512 bytes
Tamaño de sector (lógico/físico): 512 bytes / 4096 bytes
Tamaño de E/S (mínimo/óptimo): 4096 bytes / 4096 bytes
Tipo de etiqueta de disco: gpt
Identificador del disco: C271E36A-B1BA-4B61-9C48-B90831A729D5
Dispositivo Comienzo Final Sectores Tamaño Tipo
/dev/sda1 2048 1023999 1021952 499M Entorno de recuperación de Windows
/dev/sda2 1024000 1226751 202752 99M Sistema EFI
/dev/sda3 1226752 1259519 32768 16M Reservado para Microsoft
/dev/sda4 1259520 1187666070 1186406551 565.7G Datos básicos de Microsoft
/dev/sda5 1187667968 1953523711 765855744 365.2G Sistema de ficheros de Linux
I'm not sure what should I do or what all of these means, I'm not used to linux.
In BIOS I have secure boot and legacy support both disabled. I already made sure hibernate option is disabled in Windows
