Auto Updates fail ---- 200+ Sites

Hi ... first, thank you for your extensions.

I've been having an issue for about 6 months where auto updates no longer work for your plugins.

I've deleted joomla cache, etc.

Auto Updates work for other extensions, just not ones from you folks. I use add to menu, sourcer, etc.

Is there anything I can do to fix? or is the issue on your end? 200+ Joomla 3 sites that this is happening on.

I use:
add to menu
Sourcerer
Sliders
Cache Cleaner

Sorry. I just mean the joomla update. Not Auto.

Here is the message I receive from joomla after hitting "FIND UPDATES" in the EXTENSIONS->MANAGE ->UPDATES area.

Warning
Update: Could not open update site #266 "Regular Labs - Sourcerer", URL: download.regularlabs.com/updates.xml?e=sourcerer&type=.xml
Update: Could not open update site #267 "Regular Labs - Modals", URL: download.regularlabs.com/updates.xml?e=modals&type=.xml
Update: Could not open update site #268 "Regular Labs - Sliders", URL: download.regularlabs.com/updates.xml?e=sliders&type=.xml
Update: Could not open update site #270 "Regular Labs - Cache Cleaner", URL: download.regularlabs.com/updates.xml?e=cachecleaner&type=.xml
Update: Could not open update site #277 "Regular Labs - Add to Menu", URL: download.regularlabs.com/updates.xml?e=addtomenu&type=.xml


All other updates for other developer components/plugins work fine. Just the ones from you folks have this message. 2 different servers ... 200+ joomla sites.

I own the servers. I have not knowingly blocked you. What ip/ domains should be whitelisted?

Thanks ... I added you to whitelist and all working again.