home server not accessible from same LAN (on one laptop only) but works for all others

[humptydumpty]

I'm experiencing the weirdest thing. I cannot access my homeserver apps (nextcloud & vaultwarden) on a specific laptop only (it was factory reset but decided to use it today). It's connected via wifi to my network. The homeserver is connected via ethernet. I can access the homeserver from other laptops/devices, so I know the home server is working just fine. What could it be?

What I've done:

• refresh DNS cache in CMD using ipconfig /flushdns
• made sure my home IP has not changed and that DNS records for the sub/domains are valid
• port 80 and 443 are open for my IPv4 and IPv6 addresses
• connected to home server from another laptop via wifi and through a VPS to have an external test (works fine)
• connected to home server from mobile w/ wifi off and used data plan only (works fine)
• in CMD, I pinged my bare domain (which points to my VPS and it reports back), but it fails to ping the subdomain that points to my homeserver.

Why would things work on all devices but one?

[Kubernetes]

I assume that probably the IP-Address Lookup for the DNS Name is failing. When you do ping your subdomain. Does it show the correct IP-Address of your home server? (Even if the replies failing)

[humptydumpty]

@Kubernetes yes, it shows the correct home IP but fails to ping.

[girish]

Maybe there is a old router config for this laptop where you put it in a DMZ or something ? Is the laptop able to to ping other devices?

[humptydumpty]

I'll try pinging other devices when I get home, but I never set up anything like that in the router for any of my devices. I also checked all settings and firewall rules in the router yesterday in case I missed something. This laptop was used for browsing the web by a non-techie family member, so I'm positive no "tinkering" was done. It's also been factory reset (thought about selling it), so there shouldn't be any Windows settings that might be causing it. The only negative thing about this laptop is that it has soldered RAM lol. Edit: It also runs on Windows 11 How could I forget/rule that out?!

[humptydumpty]

@girish I couldn't ping other devices and then I noticed the gateway is different (via ipconfig). MB! I remembered that I'm using the guest wifi (easy to remember pass) since I can't access my vaultwarden to get the credentials for my main wifi. If I wasn't on the same network, why would my connection to the homeserver stay internal (via local IP) instead of accessing the apps thru the domain like any other website?

After connecting to the main wifi, I can access the apps/homeserver just fine.