I follow these instructions for set my raspberry pi 3 as an access point https://frillip.com/using-your-raspberry-pi-3-as-a-wifi-access-point-with-hostapd/
It works but now I want to share the connection of my clients connected on the access point for get internet on the raspberry pi.
When I use Ethernet connection I can reach natively internet network so I don't understand why it's not working with wifi in AP mode.
I'm a noobie in network management so I put some command which I hope could help you.
pi@raspberrypi:~ $ ifconfig
eth0 Link encap:Ethernet HWaddr b8:27:eb:f4:79:b4
inet6 addr: fe80::12a:d36e:817d:73c6/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:324 errors:0 dropped:0 overruns:0 frame:0
TX packets:324 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1
RX bytes:21726 (21.2 KiB) TX bytes:21726 (21.2 KiB)
wlan0 Link encap:Ethernet HWaddr b8:27:eb:a1:2c:e1
inet addr:172.24.1.1 Bcast:172.24.1.255 Mask:255.255.255.0
inet6 addr: fe80::5744:c4a:3574:d69c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1768 errors:0 dropped:1522 overruns:0 frame:0
TX packets:90 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:278297 (271.7 KiB) TX bytes:17624 (17.2 KiB)
pi@raspberrypi:~ $ ping 8.8.8.8
connect: Network is unreachable
pi@raspberrypi:~ $ sudo route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
169.254.0.0 0.0.0.0 255.255.0.0 U 303 0 0 wlan0
172.24.1.0 0.0.0.0 255.255.255.0 U 0 0 0 wlan0
At this moment I had one device connected on the AP which had internet connection.