If a student loan is wiped, does that affect entitlement to future student loans?

I know that if a person falls behind in re-repayments for an undergraduate loan they are not entitled to a postgraduate loan, BUT is legitimate deferment and eventually having a loan wiped/ written off for whatever reason, the same as failing to keep up with repayments? If it’s not the same, are they entitled to a future loan for a postgraduate degree like a masters?

I believe that the only way a student loan is wiped is if you have paid it off in full or reached the end of your payment term when the outstanding balance is written off. Under what circumstances do you think it is possible to have the loan written off?

Ok if a person has reached the end of their payment term and was allowed to defer during that period due to not having sufficient income, illness or unemployment, Is that classified as failing to keep up repayments? Are they entitled to take out future loans? Even if their employment / income status has improved.

Are you talking about UK student loans?
You don't defer payments for those due to being unemployed or in a low income role, as they you only make repayments towards your SLC student loan if earning over a specified threshold. If you are earning under that (or unemployed) you just don't make repayments at all. You don't need to do anything about this if you're a PAYE worker, as this will automatically be sorted out by your company's payroll/HR team. If you're a contractor/self employed worker then I believe this is part of the process for when you submit your self assessment form for taxes.
As above otherwise the only other situation SLC loans are written off is 30 years or 40 years after you take them out (depending which plan loans they are). I would be surprised if this itself would be a factor, but bear in mind that there are limits to taking out student loans when past retirement age as I understand (whether or not you previously had a loan and whether or not that was repaid or written off).
Many if not most people taking out a masters loan won't have finished repaying for their undergraduate student loans, and some may not have even starting repaying them. This doesn't stop them taking out the masters loan.

It was a UK student loan and they had a 25 year repayment as the loan was taken out in the mid 1990s and just covered maintenance. They’re still a long way from retirement age. The undergraduate degree (2:1) they did, should really have been continued to masters /postgraduate level to improve employability and good income. They’ve considered doing a masters, PhD or teaching.

Now that it is a bit clearer I have moved the thread to Ask SFE for further guidance.

I know that if a person falls behind in re-repayments for an undergraduate loan they are not entitled to a postgraduate loan, BUT is legitimate deferment and eventually having a loan wiped/ written off for whatever reason, the same as failing to keep up with repayments? If it’s not the same, are they entitled to a future loan for a postgraduate degree like a masters?