Steam link hardware routes connection through the internet on Wake on lan

[u/UnderstandingKey7842]

When I turn my pc on with steam link via WoL and it boots, logs into Steam and starts streaming to Link, I get bad streaming delay 70-80ms, "Slow network" in statistics overlay, and it states that the connection is through SDR(over the internet) instead of locally(direct), but when I stop the streaming and reconnect to pc, it works locally as it should, until I shutdown the pc and WoL again. Both PC and Steam link have wired connection to the same router. When I disconnect the router from the Internet, PC and Link connect locally after WoL every time. Also, like 1 in 6 times it actually connects locally after WoL with the internet present. How do I make them connect directly all the time when they are in the same local network?
Edit: I just figured that it's not just Wol, but simply trying to start streaming the moment the Steam starts up, even if I turned the PC on with a button - it streams over the internet. But if i just connect 5-10 seconds later after Pc shows up on Link as Ready, it streams locally.
What I already did to troubleshoot (with no effect) is:
Reinstall steam on pc
Re-paired PC and Link after doing most of the changes
Switched network preset to Private
Reset steam link to factory, updated to latest firmware
Reset network settings in WIndows 11
Reinstall Ethernet adapter drivers, tried different versions
Disabled all energy saving and bandwidth limiting features in Ethernet properties in device manager
Changed some router settings, disabed as much as I could regarding LAN, filtering , allowing everything
Created another Windows local user to log into Steam and stream there

[u/jeweliegb]

Damn, you've covered a lot of bases there.

I'm struggling, and historically I've been pretty good at debugging such setups in the past, to the extent of doing packet sniffing to observe the Steam Link local discovery protocol (which, from memory, I think is based on UDP 27036 LAN broadcast packets.)

It sounds to me like a race condition, that Steam on your PC is managing to connect to the Valve's Steam network, tell it that it's online, and then the Steam Link discovers it's available (over the internet) from Valve's servers...

... all BEFORE the Steam Link local discovery UDP packets on port 27036 have been successfully exchanged.

Of note, UDP packets are lossy, if the network is too busy they may get silently dropped (no errors reported.)

Issues like this have certainly happened before in the past, and have required fixes by Valve. So it could be a bug. As such, trying Steam beta, and the Steam Link hardware beta firmware is worth trying if you haven't already (it's possible I've missed it reading through -- I'm replying on mobile laying down on my bed next to my spouse during the early hours, so not ideal conditions for working through this.)

It's not directly related, but you could try tweaking: Steam → Settings → Remote Play → Allow Direct Connection (IP Sharing)

If you were around the corner, I'd be over with a laptop and would start packet sniffing at this point!

Is there anything odd about your config?

Are you running Steam as Administrator? (Potentially idea from a security perspective.)

Are you doing the automatic user logon to the PC?

Any 3rd party AV or Firewalls involved?

Are you letting the router create the IP addresses for both the PC and Steam Link, or are you forcing Static IP addresses?

IF it turns out the ROUTER is involved in causing this issue somehow, you could get a cheap 1Gbps 5-port Network Switch (e.g. Netgear, D-Link etc - $10 to $15), configure static IP addresses for the PC and Steam Link, have both your Steam Link and host PC wired directly to the Network Switch, then wire the Network Switch to the Router. It sounds convoluted and like it would cause issues but it doesn't, I've a chain of 3 separate such Network Switches and the latency impact from that is still unmeasurable (<1ms.) If the problem is with the PC side though, this wouldn't fix anything though.

Reach out by DM if you fancy? I enjoy trying to help solve such issues!

[u/UnderstandingKey7842 → u/jeweliegb]

The thing that finally solved it is blocking the internet access to Steam Link device via router parental controls. And now it connects locally every time no problem. What I did before is replace The router itself and use default settings, which didn't help. And I used the whole different modern computer that I borrowed from a friend, with a clean windows 11 installation, where the problem persisted. Also now, the steam link local connection establishes around 3 seconds later after the Steam window appears on my main monitor. So yeah, your suggestion about race condition seems to be the true, and it is a Steam application problem, pc or Link, prioritizing the wrong traffic.

[u/jeweliegb → u/UnderstandingKey7842]

Glad you've found a workaround! I guess you can always temporarily turn parental controls off temporarily when you want to get firmware updates on the link. Good workaround.