G'day,

I'm on a 100/40Mbps HFC plan, and have an ongoing issue where the internet in general (browsing, file access, email, cloud hosted products, etc) will just grind to halt.

For example, I can be accessing our CMMS and suddenly a page load will take 30+ seconds to complete. Never times out, just takes forever. Or I'm using our accounting software which syncs remotely and saving an invoice or opening a purchase order will stall for a minute.

This behaviour goes on for maybe 5 minutes or so and then goes away again. It can occur once or twice in a 10 hour day at the office, or not at all, or sometimes half a dozen times in a one hour period.

• Local network use is unaffected (for e.g. accessing SMB shares to a local server)
• All PCs and laptops connected to the LAN are affected so its not PC-specific.
• Ping is unaffected and hovers around 12ms to geographically close remote servers, with no packet loss or jitter.
• Speedtests of any kind always return around 95/35Mbps at any time be it peak / off peak / when problem is occurring / when problem is not occurring
• VOIP does not seem to be affected despite being on the same network and I can talk on the phone while the internet is otherwise wading its way through treacle.
• Happens with my current ISP (Leaptel), but also happened the previous ISP (Aussie Broadband) who are 100% completely different companies and I believe use completely different peering/routing/backhaul/etc.
• DNS seems irrelevant and occurs using either the ISP DNS, Cloudflare, Google, or Quad9
• Some websites like Facebook and Google work, but other websites like Lemmy (any instance), Reddit, my CMMS, various wholesaler sites hosted both in AU and worldwide, are affected.

Are there any steps I can take to try and identify what causes this random delay? Its just enough to be really frustrating, especially when you're trying to look up something while on the phone and have to be like "so yeah hows the wife? hows the kids? hows the....dog? .... pet bird doing anything interesting?" as you wait for a damn page to load. I need fast internet so I dont need to make small talk dammit.

PCs are all on cat5e or cat6 (depending on when the cabling was run), to a Ubiquiti Dream Machine SE which is connected via cat6 to the NBN HFC modem.