I always had my router configured with multiple WANs as a minimum I have an xDSL and an NCM modem that is used as backup. But I have also configurations with WANs on ethernet. This is to say that regardless of the hardware used for the WAN interfaces, in 21.02, with 2 WANs, one of the 2 experiences packets loss when both are up. If I take down the main one (let's say the pppoe interface), the other interface resumes working 100%. I tried with different routers models (mainly WRT32x and BT Home Hub 5) and I get always the same results.
Please see the issue I posted on the OpenWRT github tracker here:
The same configuration works flawlessy in 19.07. Periodically I try new 21.02 updates when available, but to date this issue remains unresolved.
I am hoping that someone could confirm this issue and help me resolve it. Is it a bug or a configuration issue? To me, it sounds like a bug introduced at the same time as the new switch configuration. Before that feature was introduced in 21.02, this release was working fairly well.
I already followed your link. That doesn't answer my question though. Did you verify with tcpdump that packets go out of the interface and don't return or are they spread over different wan interfaces?
Nope, I just used ping and then I had to revert to 19.07. I cannot have downtime on my WANs or the router to investigate further. I would hope that some of the developers would have a test environment to reproduce the issue.
If it was so seriously messed up, there would be numerous complaints. However we are already in the third release of 21.02 and I haven't seen such. Finally you can use the stable version instead of the snapshot.
However without any troubleshooting from your part, if the problem is not replicated or affecting anyone else, it will be difficult to get much attention.
Could you just try to setup a configuration with 2 WAN interfaces as in my example? Is it a configuration problem? Could it be that you do not see this reported because not many use 2 WANs? I have 3 different sites and all have the same issue on 2 WANs. Wether the first is pppoe and the second an NCM modem or both Ethernet or one Ethernet and one pppoe. The result does not change. One of the 2 interfaces typically the 2nd brought up, looses packets on ping.
I would be grateful if you could look into the configuration I posted and try to reproduce the issue, perhaps it is a configuration problem. In my example there are 2 ethernet WANs, but any interface type gives the same result.
No need to try, I am already running a site with 5 wans.
interface wwan is online 41h:49m:31s, uptime 53h:37m:41s and tracking is active
interface wwan1 is online 16h:11m:09s, uptime 16h:11m:12s and tracking is active
interface wwan2 is online 33h:42m:18s, uptime 33h:42m:21s and tracking is active
interface wwan3 is online 41h:22m:22s, uptime 41h:22m:25s and tracking is active
interface wwan4 is offline and tracking is paused
Heve you tried to ping a known IP (like 126.96.36.199) from each interface using
ping -c 10 -I wwan 188.8.131.52
for example to see if you lose packets?
Please could you post your configuration? What router hardware do you have?