Hey all. I'm using a two pod Deco X50 system provided by my ISP, but I have full configuration control. I've got a very strange problem here that may or may not be related to the Deco, but in 20+ years in IT, I've never seen this so I wanted to confirm.

Core problem: On one system (my main desktop), file sharing using DNS specifically will just die after some period of time. Sometimes as little as an hour, sometimes a day. What will happen is if you try to browse to a file share on another system using its DNS name, File Explorer will just spin indefinitely. If you try to go to the same share via IP address, it's fine. No other systems on the network have this issue. It's also only DNS file sharing that dies. The Internet and all other connectivity continues unimpacted. Rebooting my desktop is the only thing that fixes this, until it breaks again.

Setup: My Deco router is in my office upstairs and is connected to the fiber media converter from my ISP. It connects off to a 2.5GBit unmanaged switch, which my PC is plugged into with a 2.5GBit NIC. Nothing else is connected to the router. Another 2.5GBit switch in the basement is connected to the first one with a cable that runs through a vent. Off the switch in the basement is my server, my Philips Hue hub and a test station that's normally unplugged. My other Deco is under my TV in the living room, meshed to the first one and my game consoles and TV plug into its internal switch. My desktop and my server have consistent IP addresses that are handed out by the Deco via Address Reservation.

What I've tried: A different 2.5GBit NIC, multiple driver versions, a full reset of Windows networking and I've even gone so far as a full wipe and reload of the OS. What has seemingly solved the problem is plugging my main desktop into the Deco's internal switch, which cuts the speed down to 1GBit.

I'm baffled as to why this works. Normally I'd blame the 2.5GBit switch in my office (it's a random Chinese brand from Amazon, though most of them have the same internals), but the devices on the other switch that daisy chains off this one are unaffected. The switch is also only a few months old and nothing except this one problem presents itself. I'm fine replacing it, but I don't want to unless I'm sure that's the issue. I have read online that some people have had some weird behaviours when using specialized devices or applications on Decos because for some reason, TP-Link didn't put a DNS server on them, so they don't provide a local domain. I'm not sure why that would cause Windows file sharing to die, but it's possible maybe something's happening when IP leases expire and renew and that the switch doesn't like this?

I'm wondering if anyone else has run into this issue and knows the cause. If it is the switch, I'll order a replacement. If it's the Deco's lack of proper internal DNS, I can setup an internal DNS server on a Raspberry Pi (kind of an overkill solution, but if it works, it works). I may choose to just roll my own router at some point, but for now, I'd like to figure out a way to get reliable file sharing, while maintaining the 2.5GBit LAN speeds my switch provides.

I appreciate any help. Thanks all!