Starting emacs daemon in console as:

emacs -u user -chdir /home/user --fg-daemon=emacs.user --debug-init

outputs:

Loading t-mouse...
Loading t-mouse...done
Error setting gpm-mouse-mode: (error Gpm-mouse only works in the GNU/Linux console)
Starting Emacs daemon.

Consequently mouse won't be usable when connecting to daemon, whereas standalone emacs launched in console has mouse enabled.

Context:

cat /home/user/.emacs

;; Added by Package.el.  This must come before configurations of
;; installed packages.  Don't delete this line.  If you don't want it,
;; just comment it out by adding a semicolon to the start of the line.
;; You may delete these explanatory comments.
(package-initialize)

 (set-background-color "black")
 (set-face-background 'default "black")
 (set-face-background 'region "black")
 (set-face-foreground 'default "white")
 (set-face-foreground 'region "gray60")
 (set-foreground-color "white")
 (set-cursor-color "red")

(setq make-backup-files nil) ; stop creating backup~ files
(setq auto-save-default nil) ; stop creating #autosave# files

(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(gpm-mouse-mode t))

(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 )

NB: bug reported at https://bugs.gentoo.org/677826
Thks

In GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu)
 of 2019-02-12 built on asuslpm
Windowing system distributor 'The X.Org Foundation', version 11.0.12003000
System Description:    Gentoo Base System release 2.6

Recent messages:
Loading t-mouse...done
Loading xt-mouse...done
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --prefix=/usr --build=x86_64-pc-linux-gnu
 --host=x86_64-pc-linux-gnu --mandir=/usr/share/man
 --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc
 --localstatedir=/var/lib --disable-silent-rules
 --docdir=/usr/share/doc/emacs-26.1-r3
 --htmldir=/usr/share/doc/emacs-26.1-r3/html --libdir=/usr/lib64
 --program-suffix=-emacs-26 --infodir=/usr/share/info/emacs-26
 --localstatedir=/var
 --enable-locallisppath=/etc/emacs:/usr/share/emacs/site-lisp
 --without-compress-install --without-hesiod --without-pop
 --with-file-notification=no --disable-acl --without-dbus
 --without-modules --without-gameuser --with-gpm --without-kerberos
 --without-kerberos5 --without-lcms2 --without-xml2 --without-mailutils
 --without-selinux --without-gnutls --without-libsystemd
 --without-threads --without-wide-int --without-zlib --with-sound=oss
 --with-x --without-ns --without-gconf --without-gsettings
 --with-toolkit-scroll-bars --without-gif --without-jpeg --without-png
 --without-rsvg --without-tiff --with-xpm --without-imagemagick
 --with-xft --without-cairo --without-libotf --without-m17n-flt
 --with-x-toolkit=no 'CFLAGS=-march=native -mtune=skylake -O2 -pipe'
 CPPFLAGS= 'LDFLAGS=-Wl,-O1 -Wl,-fuse-ld=bfd -Wl,--enable-new-dtags
 -march=native -mtune=skylake -O2 -pipe''

Configured features:
XPM SOUND GPM FREETYPE XFT OLDXMENU X11

Important settings:
  value of $LANG: fr_FR.utf8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  xterm-mouse-mode: t
  gpm-mouse-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec epa derived epg gnus-util rmail
rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils elec-pair web-mode advice disp-table
xt-mouse t-mouse cus-start cus-load finder-inf package easymenu
epg-config url-handlers url-parse auth-source cl-seq eieio eieio-core
cl-macs eieio-loaddefs password-cache url-vars seq byte-opt gv bytecomp
byte-compile cconv cl-loaddefs cl-lib site-gentoo time-date mule-util
tooltip eldoc electric uniquify ediff-hook vc-hooks lisp-float-type
mwheel term/x-win x-win term/common-win x-dnd tool-bar dnd fontset image
regexp-opt fringe tabulated-list replace newcomment text-mode elisp-mode
lisp-mode prog-mode register page menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote dynamic-setting font-render-setting x multi-tty
make-network-process emacs)

Memory information:
((conses 16 127340 11451)
 (symbols 48 23547 1)
 (miscs 40 77 115)
 (strings 32 39253 1295)
 (string-bytes 1 1043338)
 (vectors 16 17583)
 (vector-slots 8 526650 8204)
 (floats 8 60 243)
 (intervals 56 307 0)
 (buffers 992 12))