"I tried extending down there, but they wouldn't accept my salary plus earnings from online teaching.", you tried to show them earnings from illegal work and they would not accept it, not really a big surprise there.

You could be asked for proof of onward travel by your air carrier, and immigration could ask you to show 20,000 baht or equivalent and proof of accommodation.

You will require the following steps to be completed; It is mandatory that the following steps are taken before the Non-Immigrant “ED” visa for the Monk can be issued:

1. Recommendation letter from the temple in Thailand sent to the Office of Buddhism, Thailand.

2. Recommendation letter from the Office of Buddhism, Thailand, sent to the Ministry of Foreign Affairs, Thailand.

3. Approval letter from the Ministry of Foreign Affairs, Thailand, sent to the Royal Thai Embassy.

4. The Royal Thai Embassy issues Non-Immigrant “ED” visa for the Monk (visa applicant)

You should apply for a Non-immigrant Education visa to study as a monk.

Guess you are talking about the ETA, which is not even going to be "soft" introduced until December this year, so in answer to your question, "no" you will not require one as they will not even be available at the time of your travel.

Both Savannakhet and Vientiene will issue, but you will need to have 400k baht seasoned for 2 months prior to application.

@Tod ********

Seems like he is in the Philippines, so be a weird one to enter via land, lol

You will need the 800k, but not the insurance, that is not a requirement for a Non-O based on retirement/over 50.

When you extended, you could have bought a re-entry then, or you could have got one at the airport before your flight. As I said, your OA extension is gone, if you wanted an OA again, you would have to apply in your home country. Or you could get an in country Non-O and then extend that, (with no health insurance requirements).

Not exactly sure what visa you had, but presumably a non-immigrant or extension thereof. Sadly the answer is whatever you had, has now gone because you did not get a re-entry permit prior to leaving the country. You are now on a visa exempt entry and will have to start all over again.