Update Systemd files: remove network requirement, reduce timer interval, other minor changes

wanchecker.service

@@ -1,8 +1,7 @@
 # Should be placed to /usr/lib/systemd/system/
 
 [Unit]
-Description=WAN IPv4 checker & email sender for dynamic IPv4 server environments
-After=network-online.target
+Description=WAN IPv4 checker & email sender for dynamic IPv4 environments
 
 [Service]
 User=mail

wanchecker.timer

@@ -3,12 +3,11 @@
 # https://wiki.archlinux.org/index.php/Systemd/Timers
 
 [Unit]
-Description=Run WAN IP checker in fixed intervals and on boot
+Description=Run WAN IP checker service in fixed intervals and on boot
 
 [Timer]
 OnBootSec=2min
-OnUnitActiveSec=20min
-Persistent=true
+OnUnitActiveSec=15min
 
 [Install]
 WantedBy=timers.target