I’d strongly recommend contacting our [U]Product Support Team[/U], it’s free and they have loads of experience troubleshooting this sort of issue.
In the meantime, I’d start by double-checking all your network settings. For example, make sure you can use PAC Manager to inspect (Tools > Inspect) both the R1 and the EB2 to make sure they have the same subnet mask, and the PC can read all those values. Sometimes that low-level ping will still work even if subnets are off/mismatched.
If you have trouble connecting to the EB2 via PAC Manager, I’d double-check to make sure you’re pinging what you thinking your pinging (especially if there are other devices on the network). E.g., while you’re pinging the EB2, disconnect the cable to the EB2, and make sure the ping stops working.
Let us know what you figure out!