Hi! The K4 ISIO only messed up the channel order for me, every time after switching off. Otherwise I couldn't find any problems. Before that I had the TechniSat Digit ISIO C, which ran wonderfully (only twin tuner). Best picture quality I have ever seen (I have had several receivers). Everything about it ran flawlessly, but I wanted to try something different with the K4. There are no differences worth mentioning for me, except for the channels. But the ISIO C is absolutely recommendable if you are considering a new purchase. Greetings, Angelo

I have had the part for a short time. Even when I unpacked it, I was worried about quality? The thing is bouncing.
It also gets very hot after a short time in operation.
And when I plugged in a USB WLAN adapter, I noticed that it only works with the one at home, as it turned out later. It didn't recognise the two adapters at home.
I hope it survives a few years, but after that there will certainly be nothing more from Technisat.

I personally have no technical problems with the set. Only the EPG is unusable.

The fifth exchange unit is now in my "test lab". My primary goal - I don't want to scrap it!

The thing is now open in front of me. What's new since my first post? I gave it a slowly rotating fan, new cables, a new TV, new USB to SATA controller, new sheath current filter (galvanic isolator on the TV coax cable), a new 220V APC voltage stabiliser, the SSD is supplied with its own power via USB hub - so everything is new. I even had the house TV system measured by an expert. You never know how the currents will flow. With the TSD format, K4 should be able to develop fully - so the whole thing now runs with TSD. Firmware 2.74.0.8 (4407), Hardware 60.0-4(V4).

Power ON! The big moment!
If I were to use the device the way over-80s usually do, zapping a little, recording two or three films at the same time, hoping that the broadcasters send the on/off signal, then the K4 device is tops!

Stupidly, as an over-80 person, I discovered the option "network standby mode" in the basic settings on the device. Being a curious person, I turned this option on because you need this option for almost all the good things you want to use on this device. If I want to mark programmes for recording via the mobile phone app/SFI - or if I want to watch a film via UPnP on my tablet (...) and so on (...)

This mode virtually ignites the turbo on the K4 device and thus stands out from the crowd.

Unfortunately, as soon as I ignite this turbo, the following happens (v2.74.0.8): a) the HDMI interface runs continuously at full load from that moment on, i.e. even if I switch off the TV, an HDMI signal can still be measured. When a TV runs for 100 hours without interruption, it's no wonder that the HDMI interface goes bye-bye after a few days. This is exactly what happened to me with two sets. To repeat, as soon as the "network ready mode" is ON, HDMI interface no longer switches off, and the device gets very hot. In turn, the heat has a detrimental effect on the operation of the unit. The consequences a) Crashes b) Boot loops c) Folder "My recordings" disappears d) HDMI port disappears e) See also PROS/CONS Amazon reviews.

My conclusion:
I think with a firmware update >v2.74.0.8 the problem should be solved somehow. The device encodes/decodes so well in real time, then it should theoretically be possible to somehow handle the small, unimportant things as a hardware/software supplier. The remote SFI and the UPnP story are cool - just awesome, if they could be switched on. But I'll leave it switched off until the next upgrade. Because as I mentioned at the beginning - my goal, the fifth device, I don't want to scrap in any case!

Feedback from Amazon reviews summarised.

PROS
+ simple operation (..) excellent picture quality (Klaus Friedrich)
+ parallel recording option of 4 programmes (Thriller Fan)
+ SFI works reliably with pre- and post-run times (Ke Ko)
+ for transfer to the PC, one attaches a second hard disk, formatted with NTFS,
and copy the recordings in the unit to it. This creates a single file (H-P).
+ Receiver runs stable - no crashes so far. Very good value (Snarrow)
+ excellent service hotline (..) very friendly and competent (E 69 driver)

CONS
- 5 times use (..) no more picture signal via HDMI (Günnie)
- always switches off after a short time and restarts (Werner)
- Unit hangs in a boot loop and nothing happens (Lars Wölk)
- Unit switches off and on again 3 times in a row (Manfred Wagner)
- During the recording tests, the receiver crashed sporadically (Raira)
- UPnP server is regularly restarted (Kanalhinnerk)
- what surprises me is the high heat development (...) however
since I provided additional cooling and the hard disk has its own
power supply, the performance and reliability of the
and reliability of the receiver have increased significantly (edwin.m)
- The HDMI cable supplied is not suitable for 4K (emptyName)

My K4 puts a lock symbol on all recordings, although parental control is deactivated everywhere. Technisat is at a loss. My old ISIO C does not do this with the same hard disk, settings and Smartcard.