Problem: TP-link Deco M5 totally limits wired transfer speed from PC to NAS (Synology DS220+)?
TL;DR: As soon as my TP-link Deco M5 is added to my network the wired(!) transfer speed between PC and Synology NAS drops down to max 355kb/s.
I recently expanded my network with a few more Deco M5 units and connected some hardware in a different location in my house.
Since then, for my Synology DS220+ NAS I have achieved a maximum (download) speed of exactly 355 kb/s in a wired connection with my PC. Resetting etc. didn't change anything. The NAS is next to my PC and they are connected to each other by ethernet cable via a switch. The switch is connected to the rest of the network via an ethernet cable to an Deco M5 unit that picks up the wifi signal from the ground floor. I added a picture below of the setup. The WiFi speed on the PC (and other devices) is excellent and way above 100 MB/s as expected.
After a lot of researcg, it turns out that the Deco network is the cause of the low speed from NAS to other units (via Ethernet cable or WiFi). As soon as I remove the network cable from the M5 unit to the switch (and the NAS and PC are only connected to each other and not to the rest of the network), I suddenly get download speeds approaching 80-100 MB/s. So the limit on the speed comes from the broader network via the Deco units.
I have checked all the settings in the Deco app but I cannot see where the cause could be. Does anyone have an idea why my Deco network is interfering with the (wired) connection between PC and NAS? And how to solve it of course.
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