My Android device (GT-S5570 running 2.2.1) is having connection problems with my home Wi-Fi network (ZyXEL adsl P-660HW-D1). The device connects ok, gets an IP address, and sees all other computers on the network (using Overlook Fing). I have good signal strength, and there are no conflicting Wi-Fi networks around.
However, ping results are rather mixed. Depending on the attempt results come back with packet loss of anything from 100% to 0%, usually one or the other, but something around 20% or 60% happens quite often too. This happens with all the devices on network, including the gateway. Other devices can ping each other just fine, independent of connection type (Wi-Fi or Ethernet wire).
There are also some other wlan problems with one (but only one!) of the computers: 1) It has some random touble connecting to the wlan (authentication failure), but when it gets a connection it stays connected without connection issues. 2) Sometimes ping results show some random packets with weirdly long latency, and occasional lost packet (<2% if even that). This would point to trouble with the Wi-Fi settings. However, the packet loss doesn't appear parallel: The Android can get packet loss while the computer at the same time reports perfect ping.
The Android device always gets a connection, and stays connected to the Wi-Fi even when it's getting 100% packet loss. The Android device also works perfect in any other Wi-Fi I've tried. Also, any visiting computer I've tried connecting to my home Wi-Fi has had no trouble.
The router has the original (which is also the latest) firmware, and I haven't meddled with the settings it came with - I woudn't know which settings to meddle with.
How do I debug this further? What Wi-Fi settings could be causing this?
(This also seems oddly similar to the trouble described in this question.)
(Cross-posted to Super User since while the main problem is with the Android device, the problem itself appears wider.)