DVLA is indeed a car-crash. For some weeks I've been trying to apply for my new licence for my upcoming 70th birthday.
Using Microsoft Edge, I'm can't to get beyond the first couple of pages before it fails. Using Google Chrome it is a bit of a nightmare because it can drop out anywhere, including the last couple of pages.
So far I am yet to complete the form.
I know from other website that when security certificates are not up to date. This sort of issue should not be a problem for a Government Agency, ultimately paid for by the tax payer.