pptp client cannot connect to watchguard pptp server

Good evening colleagues

I am using 750GL with 3.09 firmware on my remote offices as pptp clients to connect to my main site on a watchguard box.

All offices were working fine until on my main site I clustered the watchguard with a second one. Since then only one of the three mikrotiks cannot connect it’s pptp client. Status for the most time shows ‘link established’ but no traffic goes through and one my watchguard the user does not come up as connected. On my watchguard traffic monitor for this specific site shows “allowed” and no denials but still no connection.

I have opened a support case with watchguard but wanted to ask if anyone has had any similar experience and also how can I monitor the pptp traffic on the mikrotik side while it is trying to connect see if there is anything helpful there.

Many thanks