Have you tried checking if the router has updated firmware? That is the first thing that comes to mind, because a lot of these older units get abandoned by the makers and never see security fixes or stability patches. The VPN problem might actually be about something called NAT table size, which is basically how many connections the router can keep track of at once. Streaming is just one connection, but a VPN can open dozens of them at the same time, and a cheap unit will just choke on that. If the firmware is too old, you can sometimes flash it with open source software, but that is a whole other project and not for everyone. Still, it is worth a quick look before you give up on the thing completely.

Did you strip the old grease completely before you put the new stuff on, or just wipe it down and hope for the best?

Honestly, I think the extra details are what make it worth reading. A gas station outside Tucson is just a building until you mention the faded soda sign or the heat waves off the pavement, that's where the story lives.