[solved] nearly impossible to ping my tablet

[DHGE]

Does anyone experience the same problem?

[email protected]:/$ ping xperiaz4
PING xperiaz4 (192.168.178.44) 56(84) bytes of data.
64 bytes from xperiaz4 (192.168.178.44): icmp_seq=182 ttl=64 time=161 ms
64 bytes from xperiaz4 (192.168.178.44): icmp_seq=273 ttl=64 time=4.50 ms
64 bytes from xperiaz4 (192.168.178.44): icmp_seq=303 ttl=64 time=245 ms
64 bytes from xperiaz4 (192.168.178.44): icmp_seq=334 ttl=64 time=274 ms
64 bytes from xperiaz4 (192.168.178.44): icmp_seq=364 ttl=64 time=307 ms
...  ^C       
--- xperiaz4 ping statistics ---
979 packets transmitted, 28 received, [B][COLOR="Red"]97% packet loss[/COLOR][/B], time 1000555ms

Since I am on Linux file transfer from the tablet to my notebook via MTP is unreliable (works under Windows).
So over the years I am using the app "Software Data Cable" to transfer files via FTP.

I can not connect anymore to the tablet via FTP: Timeout establishing a connection

Possible culprits:
- the latest ROM 32.2.A.5.11 (had the same problems a version before)
- the latest AndroPlus kernels v42 (v40 the same)

Can anyone confirm this?
Or is there a configuration I should try to fix this?

Rather before downgrading I fire up a Windows-VM but that is s l o w

All my other devices work as they should. Only the Z4 gives me trouble lately. Pinging other devices from the tablet works.

 

[DHGE]

I downgraded the device several several versions down to ancient Lollipop - still no change.

Then having a thorough look at my router configuration I noticed that I could not change any settings there for my tablet?!
The other nodes were fine.
So I disconnect the tablet from the network, rebooted the router, deleted all the traces of the tablet there and then connected it again to the network -> PING

I still do not know what happened and why only the tablet was affected...