As mentioned in the first post. This how it looked after a fresh factory reset without any extra things and only one single device is connected. The average ping is between 50 and 100ms.

Then all the problems are gone. Ping: <1ms and high speed internet.

After factory reset (and setting for repeater):

root@GL-MT300N-V2:~# ifconfig
apcli0    Link encap:Ethernet  HWaddr E6:95:6E:04:2E:B1
          inet addr:192.168.100.9  Bcast:192.168.100.255  Mask:255.255.255.0
          UP BROADCAST RUNNING 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)

br-lan    Link encap:Ethernet  HWaddr E4:95:6E:44:2E:B1
          inet addr:192.168.8.1  Bcast:192.168.8.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:437140 errors:0 dropped:0 overruns:0 frame:0
          TX packets:523284 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:220815559 (210.5 MiB)  TX bytes:560501101 (534.5 MiB)

eth0      Link encap:Ethernet  HWaddr E4:95:6E:44:2E:B1
          inet6 addr: fe80::e695:6eff:fe44:2eb1/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:23192 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:3428961 (3.2 MiB)
          Interrupt:5

eth0.1    Link encap:Ethernet  HWaddr E4:95:6E:44:2E:B1
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:21732 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:2839332 (2.7 MiB)

eth0.2    Link encap:Ethernet  HWaddr E4:95:6E:44:2E:B1
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1446 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:494532 (482.9 KiB)

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:934 errors:0 dropped:0 overruns:0 frame:0
          TX packets:934 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:78289 (76.4 KiB)  TX bytes:78289 (76.4 KiB)

ra0       Link encap:Ethernet  HWaddr E4:95:6E:44:2E:B1
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:509659 errors:1674 dropped:0 overruns:0 frame:0
          TX packets:550868 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:243888687 (232.5 MiB)  TX bytes:559289261 (533.3 MiB)
          Interrupt:6

Everything is changing constantly and it’s hard to reproduce. Sometimes i get average ping rates of 25ms (In rare occasions) to the MT300. Sometimes 300ms… and sometimes 50ms… (measured over an 1 minute time frame)
Sometimes i get speeds of only 2Mbps and sometimes 18Mbps. But always have a RSSI of >60dB.