Good day! 
Please check this thread below to see if the comments are of any help:
If you have a VirtualBox installed, it could be the virtio-net process (virtual network adapter) running in the background. Try turning it off to see if it helps.
Last but not least, the HTTP protocol has nothing to do with the BeamMP servers, however, the SSL certificates are. It is unlikely that they are out of date or are being rejected. What is more likely though is that your machine’s time and date is incorrect (for example, you changed it to 01/01/1984 just for fun - never do this, unless you want to stay completely out-of-date and never receive any updates). So, please check if you have the correct time and date - even being off by a few hours could be crucial! If anything, could be as simple a solution as that.
Take care and be well! 