On April 6th, the VPN connection on my coworker's laptop was found to have stopped working, though it worked fine on the 3rd. They hadn't made any changes to VPN credentials, OS configurations or updates, or internet settings. The error showing up in Event Viewer is from RasClient, 20227, error 809 which points to the port blockage on the VPN server or firewall. Since all the rest of us can still get on the VPN, we know it's not the VPN server. I had the same issue on the 6th, but a factory reset of our building's modem/router cleared up the issue (likewise, I hadn't made any changes to affect my access for the 6th).
Their device is a MI424WR, firmware 40.21.24, and they also recently performed a factory reset. They called in to Verizon support, and a tech "showed" there was an issue because they could tracert to our VPN IP, but they couldn't ping it. On my computer, I'm neither able to tracert nor ping its IP address whether I'm connected to the VPN or not, so I don't think that alone is indicative of anything.
What I did find on their device is the BAYVPN portforwarding rule lists UDP Any -> 500. Would that interfere with our connection at all? We have an L2TP connection for our company. Is there a way to definitively show whether or not the Verizon device is blocking their VPN connection to our work network?
That includes the firewall setting(s) in the router.
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The settings that the article points to aren't specific enough for the MI424WR. I'm looking for instructions that take me through step by step on this particular router, so the article wasn't of any help.