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Random connection errors in both frontend and dashboard

I’m using WPMUDEV Hosting, and for the last few days (or maybe a week?) I keep randomly getting “This site can’t be reached” errors where my site becomes unresponsive for a minute or so before going back to normal after the page eventually reloads. There are two different types of that error message that I get, and I can’t figure out when either is triggered.

Error 1: ERR_CONNECTION_CLOSED
Error 2: ERR_HTTP2_PING_FAILED

I’ve just spent the last few hours troubleshooting, and here’s what I’ve come up with so far…

1. It’s somehow isolated to the browser it happens in, meaning if it’s happening in Chrome, I can open Opera or an Incognito window, and it will be fine in there…but then later on might be happening there and fine in the first Chrome window again. Because of this, I can’t seem to see any issues in the server error logs that I can find.

2. It affects both the WordPress admin and the frontend of the site, including any new tabs that are opened.

3. When it happens, it starts by just a blank white screen for about a minute and the status text in the bottom-left corner of the browser window says “waiting for (sitedomain)”. After it’s finished it’s timeout period, it displays one of the error messages, and then either automatically reloads the page fine, or it can be manually reloaded and works again. (Until it happens again a few minutes later, of course.)

4. Once it has actually displayed the error message, it reloads fine and any/all other tabs in the broswer for the same site start working again as well. (There’s just that looong wait with the blank white page while it attempts to load before it gets to the error message.)

5. I deactivated all plugins (except WPMUDEV Dashboard) and switched to default twenty-twenty-one theme, and I still got the errors.

6. I closed all other borswer tabs, emptied the browser cache, and then restarted the browser, and still get the error messages.

7. I cleared the “Object Cache” in the WPMUDEV hosting dahsboard, and still no luck.

8. I’m now stumped and feeling frustrated and desperate.

Fri, 30 Jul 2021 9:01:04
  • Adam
    • Support Gorilla

    Hi Josh

    I hope you’re well today!

    I checked your site, server and server logs and I must say I don’t really see anything “unusual” there at the moment. I didn’t experience such behavior there as well.

    There are some things, however, that concern me a bit:

    1. In last days there were some days of “spikes” of requests – not necessarily a traffic in general but requests made to server.

    We’ve checked and there’s no sign of site possibly being under any “bot attack” but such increase of requests might be relevant, especially that site is on a most basic (bronze) plan while it at the same time uses some complex directory plugin and a membership plugin (plugins like these are not particularly “nice” if it comes to resource usage).

    I’m not quite sure what caused that requests “peaks” but I there’s another thing that may be related to it possibly:

    2. We’ve been experiencing some temporary issues with Smush API over last couple of days (see: https://status.wpmudev.com/) and there are entries in a slow log related to Smush; that suggests that there might have been some image optimization running while there was an issue with API so that could have causes some temporarily increased load on server.

    The API issue, however, is already fixed so that part should be fine now.

    That said, you mentioned that you’ve been experiencing that recently so it’s clear that “something” must have changed recently but to make sure

    – are you still experiencing it today too?
    – you mentioned you was able to kinda “isolate” it to Chrome browser only – any specific version, tested on different OS or any specific?
    – how often does it happen/was it happening to you? I’m asking this because I wasn’t able to see/replicate that on your site (with recent Chrome on Win10) and I’m wondering if I should just try way more times or wait and try again or maybe take some specific steps?

    Let me know, please.

    Also, I noticed that you have Static Cache disabled on server.

    Is there any reason for this? Static cache can not only speed up the site but would also help a lot with preventing server resource overload and handling any “request spikes” and, unless there’s some very specific reason for keeping it off, I would sincerely recommend enabling it.

    Best regards,
    Adam

  • Josh
    • Flash Drive

    Thanks so much for looking into this Adam. I’ve been unable to work on this over the weekend, but am back at it again later today, so I’ll do some more testing, taking into consideration the points you’ve highlighted, and see if it’s still an issue. (And will then report back here.)

    And I’ve had static cache disabled while I’ve been doing active development on the site.

  • Josh
    • Flash Drive

    Hi again,
    I’m going to need some more support here. I’m still experiencing the issue, and just transferred another website over to WPMUDEV hosting, and it is also now having the same issue, (it wasn’t before transferring).

    Both website’s are large, yes, but as you can see in my account, they are both now on the Silver hosting and still experience it. (They’re the only Silver hosting sites in my account.)

    Yes, they use numerous directory and member plugins, but as stated in my first post, I still experienced the issue with all plugins deactivated, and while using a default theme.

    I experience the issue on the latest versions of both Chrome and Opera, on Windows 10.

    I am still experienceing the issue today, sometimes once every 15 mins or so.

  • Adam
    • Support Gorilla

    Hi Josh

    Thanks for response and additional information!

    This gets a bit “weirder” now and definitely we’ll need to investigate it more. I’m saying “weirder” because we are now dealing with two sites that, if I correctly understand, are complex but are not identical in terms of configuration. Furthermore, they are on two separate servers – as on our hosting each site has it’s own dedicated (separate form each other) droplets.

    I will need to “dig around” more (probably also include our devops in the case) but could you, please, grant support access to both these sites (“WPMU DEV -> Support -> Support Access -> Grant support access” in site’s back-end)?

    Let me know once it’s done and we’ll look into it again.

    Kind regards,
    Adam

  • Josh
    • Flash Drive

    Thanks Adam, glad to know I’m not the only one confused about this.
    I can think of a potential area to investigate, both sites were transferred from the same VPS account with InMotion Hosting, so I wonder if there’s some lingering configuration that came from there?

    I have enabled support access on both sites. (The issue happend again on both sites while trying to do this.)

  • Arjay Lazaro
    • Acccounts and Billing - BL

    Hi Josh,

    I hope you are doing well and I am sorry to hear about the persistent issue with your websites.

    These
    Error 1: ERR_CONNECTION_CLOSED
    Error 2: ERR_HTTP2_PING_FAILED

    Are specific and exclusive to Chrome. Both of which indicate an error connecting to the site(s).
    One in particular “ERR_HTTP2_PING_FAILED” is attributed to your Browser > Local Network > then finally ISP. It is not that ISP is not working 100% but the issue may indeed be present on the computer you are using, Browser, or your (Router) Network connection. When this fails, it is because some network device (probably a NATting device) somewhere in the path between your browser and the server has decided to drop the connection without sending an RST to the sides of the connection.

    Out of curiosity, does the issue ONLY happens with your Chrome Browser?
    As you mentioned:

    if it’s happening in Chrome, I can open Opera or an Incognito window, and it will be fine in there…but then, later on, might be happening there and fine in the first Chrome window again.

    So wondering if it’s stable with Opera? Have you tried installing or using Firefox plainly for testing purposes? Also, does the same issue occurs when testing using a totally different Device on a different Network/ISP ? How does it behave when using Mobile Phone using Mobile Data (NOT WIFI).

    I and Adam have checked your site, server, and server logs. Still, as of today, no significant log indicates any error related to the site being inaccessible. Although I saw via our Uptime that the site has gone down with 2 Outages on Sun, Aug 1, 2021. But that’s all there is.

    Please let me know how it goes when testing using different Device already on a different Network/ISP.

    Do let me know if you have further questions or inquiries. I will be glad to assist you.

    Best regards,
    Arjay L.

  • Josh
    • Flash Drive

    Thanks Adam and Arjay,

    I haven’t been able to test on a different network yet, but both ERR_CONNECTION_CLOSED and ERR_HTTP2_PING_FAILED also happen in the Opera browser, although the wording of the second might be slightly different.

    I tried resetting/restarting my local router, but still experience the issue with those error messages in both Chrome and Opera. Firefox seems to experience the same issue, but doesn’t display an error message, it just has the long delay (like a minute) and then either reloads the page or loads a blank white page with no message or content at all.

    I’ll keep trying to test from a different network in the meantime.

  • Adam
    • Support Gorilla

    Hi Josh

    Thanks for response!

    I’ll keep trying to test from a different network in the meantime.

    Please do and update us here after that. It seems very important in context of the issue. If you are using Opera it would also be great if you could additionally test if the behavior is the same or different if you enable built-in Opera VPN and try accessing the site through it.

    Best regards,
    Adam

  • Adam
    • Support Gorilla

    Hi Josh

    Yes, I am using the default VPN built in to Opera.

    So there’s no difference then with- and without that VPN and it also doesn’t matter what region you select for Opera’s VPN, right?

    Let’s see about different networks and device(s) then. Update us here, please, once you got that tested and we’ll see what to do next to pinpoint the issue and find solution.

    Best regards,
    Adam