That's exactly why I stay in my own solo public lobby. In case anyone doesn't know how to do this on the PC:
Step 1: Open Windows firewall.
Step 2: Click on advanced settings.
Step 3: Click on outbound rules.
Step 4: Select new rule.
Step 5: Select port.
Step 6: Select UDP + Specific Remote Ports (and then enter 6672)
Step 7: Click on Block The Connection.
Step 8: Check All 3 on the following page.
Step 9: Give it a name (Like... "freeeeedddooommm")
RESULT: Smooth PRIVATE lobby... every... single... time with no issues. Been having it like this since August of last year, and I'm pretty much on at least 3-4 times a week. Also, if you need to go in a public session for whatever reason, simply follow steps 1-3, and then in the middle list, click on the name you gave your setting in step 9 above, and click on "Disable Rule". When you're ready to go back to a private lobby again, simply click on "Enable Rule". And no, this is not against R* policy.
Oh yeah, one more thing, you can also invite your friends into your private lobby as well with this method and they can benefit too. I do this with my son all the time.
It does not work for me , maybe because i have static IP and NAT:Open
i just use a lag switch...been using it since crate days when i want to be alone.