I'm using a new C2600 with OpenWRT 18.06.2 and since then my eBay and AliExpress app stopped working on my smartphone.
I already resetted the apps but nothing changed. I can browse normally on the eBay website.
Too bad it didn't solve the loading issue of the eBay app which drives me crazy. I have the feeling the problem wasn't IPv6.
What makes me wonder: the eBay app is loading on the smartphone of my wife. That should than normally a problem of my smartphone but why this only happens when I'm connected to my home wifi and not when I'm connected to my corporate wifi or on the 4g network?
I'm currently preparing a Netgear EX6150v2 as a router and I will test it with this device. Maybe then it's working. If not, then it has to be my smartphone or the combination of the installed OpenWRT firmware and my client.
Okay, thanks to the great help of the forum I could use my Netgear EX6150v2 as a router. Unfortunaly it doesn't change the behavior of my smartphone. Some apps won't load and some of them feel laggy (messages in telegram are very delayed).
I switched to a third router: A Linksys EA8300 with stock firmware. This time I have more luck and my smartphone works as intended. That's pretty strange! I also performed a IPv6 test and on all devices I have full IPv6 connectivity.
Than I thought maybe the wlan drivers (all ath10k) are not working in the combination with my smartphone. But I'm using a second access point upstairs for better wifi coverage. It's a TP-Link WDR4300 with stock firmware and when my smartphone is connected there, it doesn't change anything. This means if the main router working fully for my smartphone than also the AP is working fine. If the main router not behave as intended than also the AP won't.
This leads me to the conclusion that the wifi part is not the problem and it has to do with my wired lan traffic (or routing or firewalling). Maybe someone has the right idea? Tomorrow I will test a really old Netgear WNDR3800 with OpenWRT (version 12.xx?) and look what happens.
Ok, now I have the old WNDR3800 with OpenWrt Attitude Adjustment r33624 / LuCI Trunk (trunk+svn9348) running. I know, it's a totally outdated version, but I just want to try it. I have no IPv6 Support and I still can't use my eBay or Amazon Alexa app on my smartphone.
Now it's the question what does OpenWRT different in comparison with all other routers with factory firmware? Is there a good way to sniff the packets from my android phone while try to start the non loading apps and then the same case with a working router?
I have the feeling that something like UPnP in these consumer devices are open all ports in the firewall or something.